api: Flatten and simplify Servo preferences (#34966)

Flatten and simplify Servo's preferences code. In addition, have both
preferences and options passed in as arguments to `Servo::new()` and
make sure not to use the globally set preferences in `servoshell` (as
much as possible now).

Instead of a complex procedural macro to generate preferences, just
expose a very simple derive macro that adds string based getters and
setters.

- All command-line parsing is moved to servoshell.
- There is no longer the concept of a missing preference.
- Preferences no longer have to be part of the resources bundle because
  they now have reasonable default values.
- servoshell specific preferences are no longer part of the preferences
  exposed by the Servo API.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

316 files changed, 2073 insertions, 3220 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 0c17fb13f03..c0459162263 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -949,7 +949,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "117725a109d387c937a1533ce01b450cbde6b88abceea8473c4d7a85853cda3c"
 dependencies = [
  "lazy_static",
- "windows-sys 0.59.0",
+ "windows-sys 0.48.0",
 ]
 
 [[package]]
@@ -1854,7 +1854,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "33d852cb9b869c2a9b3df2f71a3074817f01e1844f839a144f5fcef059a4eb5d"
 dependencies = [
  "libc",
- "windows-sys 0.59.0",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -2375,7 +2375,7 @@ dependencies = [
  "gobject-sys",
  "libc",
  "system-deps",
- "windows-sys 0.59.0",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -4160,7 +4160,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fc2f4eb4bc735547cfed7c0a4922cbd04a4655978c09b54f1f7b228750664c34"
 dependencies = [
  "cfg-if",
- "windows-targets 0.52.6",
+ "windows-targets 0.48.5",
 ]
 
 [[package]]
@@ -6025,7 +6025,7 @@ dependencies = [
  "errno",
  "libc",
  "linux-raw-sys",
- "windows-sys 0.59.0",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -6619,29 +6619,24 @@ dependencies = [
 name = "servo_config"
 version = "0.0.1"
 dependencies = [
- "dirs",
- "embedder_traits",
  "euclid",
- "getopts",
  "log",
- "num_cpus",
  "serde",
  "serde_json",
- "servo_config_plugins",
+ "servo_config_macro",
  "servo_geometry",
  "servo_url",
  "style_config",
- "url",
 ]
 
 [[package]]
-name = "servo_config_plugins"
+name = "servo_config_macro"
 version = "0.0.1"
 dependencies = [
- "itertools 0.13.0",
  "proc-macro2",
  "quote",
  "syn",
+ "synstructure",
 ]
 
 [[package]]
@@ -6721,6 +6716,7 @@ dependencies = [
  "backtrace",
  "cc",
  "cfg-if",
+ "dirs",
  "egui",
  "egui-winit",
  "egui_glow",
@@ -7312,7 +7308,7 @@ dependencies = [
  "getrandom",
  "once_cell",
  "rustix",
- "windows-sys 0.59.0",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -8595,7 +8591,7 @@ version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf221c93e13a30d793f7645a0e7762c55d169dbb0a49671918a2319d289b10bb"
 dependencies = [
- "windows-sys 0.59.0",
+ "windows-sys 0.48.0",
 ]
 
 [[package]]
diff --git a/components/bluetooth/lib.rs b/components/bluetooth/lib.rs
index d2476c7f371..eb380429d0d 100644
--- a/components/bluetooth/lib.rs
+++ b/components/bluetooth/lib.rs
@@ -76,7 +76,7 @@ pub trait BluetoothThreadFactory {
 impl BluetoothThreadFactory for IpcSender<BluetoothRequest> {
     fn new(embedder_proxy: EmbedderProxy) -> IpcSender<BluetoothRequest> {
         let (sender, receiver) = ipc::channel().unwrap();
-        let adapter = if pref!(dom.bluetooth.enabled) {
+        let adapter = if pref!(dom_bluetooth_enabled) {
             BluetoothAdapter::new()
         } else {
             BluetoothAdapter::new_mock()
diff --git a/components/compositing/compositor.rs b/components/compositing/compositor.rs
index ff3d62e8868..3f8bf0c1c3f 100644
--- a/components/compositing/compositor.rs
+++ b/components/compositing/compositor.rs
@@ -2303,7 +2303,7 @@ impl<Window: WindowMethods + ?Sized> IOCompositor<Window> {
         self.assert_gl_framebuffer_complete();
 
         // Set the viewport background based on prefs.
-        let color = servo_config::pref!(shell.background_color.rgba);
+        let color = servo_config::pref!(shell_background_color_rgba);
         gl.clear_color(
             color[0] as f32,
             color[1] as f32,
diff --git a/components/config/Cargo.toml b/components/config/Cargo.toml
index ea2feb49b5e..450e6298471 100644
--- a/components/config/Cargo.toml
+++ b/components/config/Cargo.toml
@@ -12,18 +12,11 @@ name = "servo_config"
 path = "lib.rs"
 
 [dependencies]
-embedder_traits = { workspace = true }
 euclid = { workspace = true }
-getopts = { workspace = true }
 log = { workspace = true }
-num_cpus = { workspace = true }
 serde = { workspace = true, features = ["derive"] }
 serde_json = { workspace = true }
-servo_config_plugins = { path = "../config_plugins" }
+servo_config_macro = { path = "macro" }
 servo_geometry = { path = "../geometry" }
 servo_url = { path = "../url" }
 style_config = { workspace = true }
-url = { workspace = true }
-
-[target.'cfg(not(any(target_os = "android", target_env = "ohos")))'.dependencies]
-dirs = "5.0"
diff --git a/components/config/basedir.rs b/components/config/basedir.rs
deleted file mode 100644
index 2fa70408a34..00000000000
--- a/components/config/basedir.rs
+++ /dev/null
@@ -1,44 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
-
-//! Contains routines for retrieving default config directories.
-//! For linux based platforms, it uses the XDG base directory spec but provides
-//! similar abstractions for non-linux platforms.
-
-use std::path::PathBuf;
-
-#[cfg(all(
-    unix,
-    not(target_os = "macos"),
-    not(target_os = "ios"),
-    not(target_os = "android"),
-    not(target_env = "ohos")
-))]
-pub fn default_config_dir() -> Option<PathBuf> {
-    let mut config_dir = ::dirs::config_dir().unwrap();
-    config_dir.push("servo");
-    config_dir.push("default");
-    Some(config_dir)
-}
-
-#[cfg(any(target_os = "android", target_env = "ohos"))]
-pub fn default_config_dir() -> Option<PathBuf> {
-    None
-}
-
-#[cfg(target_os = "macos")]
-pub fn default_config_dir() -> Option<PathBuf> {
-    // FIXME: use `config_dir()` ($HOME/Library/Preferences)
-    // instead of `data_dir()` ($HOME/Library/Application Support) ?
-    let mut config_dir = ::dirs::data_dir().unwrap();
-    config_dir.push("Servo");
-    Some(config_dir)
-}
-
-#[cfg(target_os = "windows")]
-pub fn default_config_dir() -> Option<PathBuf> {
-    let mut config_dir = ::dirs::config_dir().unwrap();
-    config_dir.push("Servo");
-    Some(config_dir)
-}
diff --git a/components/config/lib.rs b/components/config/lib.rs
index ce19ea49849..5ecd439d801 100644
--- a/components/config/lib.rs
+++ b/components/config/lib.rs
@@ -4,9 +4,6 @@
 
 #![deny(unsafe_code)]
 
+pub mod opts;
 pub mod pref_util;
 pub mod prefs;
-
-pub mod basedir;
-#[allow(unsafe_code)]
-pub mod opts;
diff --git a/components/config_plugins/Cargo.toml b/components/config/macro/Cargo.toml
index 8c94090a61d..17ff88fbe9f 100644
--- a/components/config_plugins/Cargo.toml
+++ b/components/config/macro/Cargo.toml
@@ -1,5 +1,5 @@
 [package]
-name = "servo_config_plugins"
+name = "servo_config_macro"
 version.workspace = true
 authors.workspace = true
 license.workspace = true
@@ -8,12 +8,12 @@ publish.workspace = true
 rust-version.workspace = true
 
 [lib]
-name = "servo_config_plugins"
+name = "servo_config_macro"
 proc-macro = true
 path = "lib.rs"
 
 [dependencies]
-itertools = { workspace = true }
 proc-macro2 = { workspace = true }
 quote = { workspace = true }
 syn = { workspace = true }
+synstructure = { workspace = true }
diff --git a/components/config/macro/lib.rs b/components/config/macro/lib.rs
new file mode 100644
index 00000000000..da5d3635bc8
--- /dev/null
+++ b/components/config/macro/lib.rs
@@ -0,0 +1,55 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use proc_macro2::TokenStream;
+use quote::quote;
+use syn::{Data, Fields};
+use synstructure::decl_derive;
+
+decl_derive!([ServoPreferences] => servo_preferences_derive);
+
+/// A derive macro that adds string-based getter and setter for each field of this struct
+/// (enums and other types are not supported). Each field must be able to be convertable
+/// (with `into()`) into a `PrefValue`.
+fn servo_preferences_derive(input: synstructure::Structure) -> TokenStream {
+    let ast = input.ast();
+
+    let Data::Struct(ref data) = ast.data else {
+        unimplemented!();
+    };
+    let Fields::Named(ref named_fields) = data.fields else {
+        unimplemented!()
+    };
+
+    let mut get_match_cases = quote!();
+    for field in named_fields.named.iter() {
+        let name = field.ident.as_ref().unwrap();
+        get_match_cases.extend(quote!(stringify!(#name) => self.#name.clone().into(),))
+    }
+
+    let mut set_match_cases = quote!();
+    for field in named_fields.named.iter() {
+        let name = field.ident.as_ref().unwrap();
+        set_match_cases.extend(quote!(stringify!(#name) => self.#name = value.try_into().unwrap(),))
+    }
+
+    let structure_name = &ast.ident;
+    quote! {
+        impl #structure_name {
+            pub fn get_value(&self, name: &str) -> PrefValue {
+                match name {
+                    #get_match_cases
+                    _ => { panic!("Unknown preference: {:?}", name); }
+                }
+            }
+
+            pub fn set_value(&mut self, name: &str, value: PrefValue) {
+                match name {
+                    #set_match_cases
+                    _ => { panic!("Unknown preference: {:?}", name); }
+                }
+            }
+        }
+    }
+}
diff --git a/components/config/opts.rs b/components/config/opts.rs
index 22e16286254..5b31ba595cf 100644
--- a/components/config/opts.rs
+++ b/components/config/opts.rs
@@ -6,22 +6,13 @@
 //! from command line arguments.
 
 use std::default::Default;
-use std::fs::{self, File};
-use std::io::Read;
-use std::path::{Path, PathBuf};
-use std::sync::atomic::{AtomicBool, Ordering};
+use std::path::PathBuf;
 use std::sync::{LazyLock, RwLock, RwLockReadGuard};
-use std::{env, process};
 
 use euclid::Size2D;
-use getopts::{Matches, Options};
-use log::error;
 use serde::{Deserialize, Serialize};
 use servo_geometry::DeviceIndependentPixel;
 use servo_url::ServoUrl;
-use url::{self, Url};
-
-use crate::{pref, set_pref};
 
 /// Global flags for Servo, currently set on the command line.
 #[derive(Clone, Debug, Deserialize, Serialize)]
@@ -69,13 +60,6 @@ pub struct Opts {
     /// behavior for debugging purposes.
     pub debug: DebugOptions,
 
-    /// Port number to start a server to listen to remote Firefox devtools connections.
-    /// 0 for random port.
-    pub devtools_port: u16,
-
-    /// Start the devtools server at startup
-    pub devtools_server_enabled: bool,
-
     /// `None` to disable WebDriver or `Some` with a port number to start a server to listen to
     /// remote WebDriver commands.
     pub webdriver_port: Option<u16>,
@@ -113,9 +97,6 @@ pub struct Opts {
     /// Directory for a default config directory
     pub config_dir: Option<PathBuf>,
 
-    /// Print the version and exit.
-    pub is_printing_version: bool,
-
     /// Path to PEM encoded SSL CA certificate store.
     pub certificate_path: Option<String>,
 
@@ -137,14 +118,6 @@ pub struct Opts {
     pub print_pwm: bool,
 }
 
-fn print_usage(app: &str, opts: &Options) {
-    let message = format!(
-        "Usage: {} [ options ... ] [URL]\n\twhere options include",
-        app
-    );
-    println!("{}", opts.usage(&message));
-}
-
 /// Debug options for Servo, currently set on the command line with -Z
 #[derive(Clone, Debug, Default, Deserialize, Serialize)]
 pub struct DebugOptions {
@@ -278,104 +251,6 @@ impl DebugOptions {
 
         Ok(())
     }
-
-    fn print_usage(app: &str) {
-        fn print_option(name: &str, description: &str) {
-            println!("\t{:<35} {}", name, description);
-        }
-
-        println!(
-            "Usage: {} debug option,[options,...]\n\twhere options include\n\nOptions:",
-            app
-        );
-
-        print_option(
-            "bubble-inline-sizes-separately",
-            "Bubble intrinsic widths separately like other engines.",
-        );
-        print_option(
-            "convert-mouse-to-touch",
-            "Send touch events instead of mouse events",
-        );
-        print_option(
-            "disable-canvas-aa",
-            "Disable antialiasing on the HTML canvas element.",
-        );
-        print_option(
-            "disable-share-style-cache",
-            "Disable the style sharing cache.",
-        );
-        print_option(
-            "disable-subpixel-aa",
-            "Disable subpixel text antialiasing overriding preference.",
-        );
-        print_option("disable-text-aa", "Disable antialiasing of rendered text.");
-        print_option(
-            "dump-stacking-context-tree",
-            "Print the stacking context tree after each layout.",
-        );
-        print_option(
-            "dump-display-list",
-            "Print the display list after each layout.",
-        );
-        print_option(
-            "dump-display-list-json",
-            "Print the display list in JSON form.",
-        );
-        print_option(
-            "dump-flow-tree",
-            "Print the flow tree (Layout 2013) or fragment tree (Layout 2020) after each layout.",
-        );
-        print_option(
-            "dump-rule-tree",
-            "Print the style rule tree after each layout.",
-        );
-        print_option(
-            "dump-style-tree",
-            "Print the DOM with computed styles after each restyle.",
-        );
-        print_option("dump-style-stats", "Print style statistics each restyle.");
-        print_option("gc-profile", "Log GC passes and their durations.");
-        print_option(
-            "load-webfonts-synchronously",
-            "Load web fonts synchronously to avoid non-deterministic network-driven reflows",
-        );
-        print_option(
-            "parallel-display-list-building",
-            "Build display lists in parallel.",
-        );
-        print_option("precache-shaders", "Compile all shaders during init.");
-        print_option(
-            "profile-script-events",
-            "Enable profiling of script-related events.",
-        );
-        print_option(
-            "relayout-event",
-            "Print notifications when there is a relayout.",
-        );
-        print_option("replace-surrogates", "Replace unpaires surrogates in DOM strings with U+FFFD. See https://github.com/servo/servo/issues/6564");
-        print_option(
-            "show-fragment-borders",
-            "Paint borders along fragment boundaries.",
-        );
-        print_option(
-            "show-parallel-layout",
-            "Mark which thread laid each flow out with colors.",
-        );
-        print_option(
-            "signpost",
-            "Emit native OS signposts for profile events (currently macOS only)",
-        );
-        print_option(
-            "trace-layout",
-            "Write layout trace to an external file for debugging.",
-        );
-        print_option("wr-stats", "Show WebRender profiler on screen.");
-
-        println!();
-
-        process::exit(0)
-    }
 }
 
 #[derive(Clone, Debug, Deserialize, Serialize)]
@@ -385,18 +260,6 @@ pub enum OutputOptions {
     Stdout(f64),
 }
 
-fn args_fail(msg: &str) -> ! {
-    eprintln!("{}", msg);
-    process::exit(1)
-}
-
-static MULTIPROCESS: AtomicBool = AtomicBool::new(false);
-
-#[inline]
-pub fn multiprocess() -> bool {
-    MULTIPROCESS.load(Ordering::Relaxed)
-}
-
 pub fn default_opts() -> Opts {
     Opts {
         legacy_layout: false,
@@ -410,8 +273,6 @@ pub fn default_opts() -> Opts {
         output_file: None,
         headless: false,
         hard_fail: true,
-        devtools_port: 0,
-        devtools_server_enabled: false,
         webdriver_port: None,
         initial_window_size: Size2D::new(1024, 740),
         screen_size_override: None,
@@ -423,7 +284,6 @@ pub fn default_opts() -> Opts {
         debug: Default::default(),
         exit_after_load: false,
         config_dir: None,
-        is_printing_version: false,
         shaders_dir: None,
         certificate_path: None,
         ignore_certificate_errors: false,
@@ -434,392 +294,12 @@ pub fn default_opts() -> Opts {
     }
 }
 
-pub fn from_cmdline_args(mut opts: Options, args: &[String]) -> ArgumentParsingResult {
-    let (app_name, args) = args.split_first().unwrap();
-
-    opts.optflag("", "legacy-layout", "Use the legacy layout engine");
-    opts.optopt("o", "output", "Output file", "output.png");
-    opts.optopt("s", "size", "Size of tiles", "512");
-    opts.optflagopt(
-        "p",
-        "profile",
-        "Time profiler flag and either a TSV output filename \
-         OR an interval for output to Stdout (blank for Stdout with interval of 5s)",
-        "10 \
-         OR time.tsv",
-    );
-    opts.optflagopt(
-        "",
-        "profiler-trace-path",
-        "Path to dump a self-contained HTML timeline of profiler traces",
-        "",
-    );
-    opts.optflagopt(
-        "m",
-        "memory-profile",
-        "Memory profiler flag and output interval",
-        "10",
-    );
-    opts.optflag("x", "exit", "Exit after load flag");
-    opts.optopt(
-        "y",
-        "layout-threads",
-        "Number of threads to use for layout",
-        "1",
-    );
-    opts.optflag(
-        "i",
-        "nonincremental-layout",
-        "Enable to turn off incremental layout.",
-    );
-    opts.optflagopt(
-        "",
-        "userscripts",
-        "Uses userscripts in resources/user-agent-js, or a specified full path",
-        "",
-    );
-    opts.optmulti(
-        "",
-        "user-stylesheet",
-        "A user stylesheet to be added to every document",
-        "file.css",
-    );
-    opts.optopt(
-        "",
-        "shaders",
-        "Shaders will be loaded from the specified directory instead of using the builtin ones.",
-        "",
-    );
-    opts.optflag("z", "headless", "Headless mode");
-    opts.optflag(
-        "f",
-        "hard-fail",
-        "Exit on thread failure instead of displaying about:failure",
-    );
-    opts.optflag(
-        "F",
-        "soft-fail",
-        "Display about:failure on thread failure instead of exiting",
-    );
-    opts.optflagopt("", "devtools", "Start remote devtools server on port", "0");
-    opts.optflagopt(
-        "",
-        "webdriver",
-        "Start remote WebDriver server on port",
-        "7000",
-    );
-    opts.optopt(
-        "",
-        "window-size",
-        "Set the initial window size in logical (device independenrt) pixels",
-        "1024x740",
-    );
-    opts.optopt(
-        "",
-        "screen-size",
-        "Override the screen resolution in logical (device independent) pixels",
-        "1024x768",
-    );
-    opts.optflag("M", "multiprocess", "Run in multiprocess mode");
-    opts.optflag("B", "bhm", "Background Hang Monitor enabled");
-    opts.optflag("S", "sandbox", "Run in a sandbox if multiprocess");
-    opts.optopt(
-        "",
-        "random-pipeline-closure-probability",
-        "Probability of randomly closing a pipeline (for testing constellation hardening).",
-        "0.0",
-    );
-    opts.optopt(
-        "",
-        "random-pipeline-closure-seed",
-        "A fixed seed for repeatbility of random pipeline closure.",
-        "",
-    );
-    opts.optmulti(
-        "Z",
-        "debug",
-        "A comma-separated string of debug options. Pass help to show available options.",
-        "",
-    );
-    opts.optflag("h", "help", "Print this message");
-    opts.optopt(
-        "",
-        "resources-path",
-        "Path to find static resources",
-        "/home/servo/resources",
-    );
-    opts.optopt(
-        "",
-        "certificate-path",
-        "Path to find SSL certificates",
-        "/home/servo/resources/certs",
-    );
-    opts.optflag(
-        "",
-        "ignore-certificate-errors",
-        "Whether or not to completely ignore certificate errors",
-    );
-    opts.optopt(
-        "",
-        "content-process",
-        "Run as a content process and connect to the given pipe",
-        "servo-ipc-channel.abcdefg",
-    );
-    opts.optopt(
-        "",
-        "config-dir",
-        "config directory following xdg spec on linux platform",
-        "",
-    );
-    opts.optflag("v", "version", "Display servo version information");
-    opts.optflag("", "unminify-js", "Unminify Javascript");
-    opts.optflag("", "print-pwm", "Print Progressive Web Metrics");
-    opts.optopt(
-        "",
-        "local-script-source",
-        "Directory root with unminified scripts",
-        "",
-    );
-    opts.optflag("", "unminify-css", "Unminify Css");
-
-    let opt_match = match opts.parse(args) {
-        Ok(m) => m,
-        Err(f) => args_fail(&f.to_string()),
-    };
-
-    if opt_match.opt_present("h") || opt_match.opt_present("help") {
-        print_usage(app_name, &opts);
-        process::exit(0);
-    };
-
-    // If this is the content process, we'll receive the real options over IPC. So just fill in
-    // some dummy options for now.
-    if let Some(content_process) = opt_match.opt_str("content-process") {
-        MULTIPROCESS.store(true, Ordering::SeqCst);
-        return ArgumentParsingResult::ContentProcess(opt_match, content_process);
-    }
-
-    let mut debug_options = DebugOptions::default();
-    for debug_string in opt_match.opt_strs("Z") {
-        if let Err(e) = debug_options.extend(debug_string) {
-            args_fail(&format!("error: unrecognized debug option: {}", e));
-        }
-    }
-
-    if debug_options.help {
-        DebugOptions::print_usage(app_name)
-    }
-
-    let tile_size: usize = match opt_match.opt_str("s") {
-        Some(tile_size_str) => tile_size_str
-            .parse()
-            .unwrap_or_else(|err| args_fail(&format!("Error parsing option: -s ({})", err))),
-        None => 512,
-    };
-
-    // If only the flag is present, default to a 5 second period for both profilers
-    let time_profiling = if opt_match.opt_present("p") {
-        match opt_match.opt_str("p") {
-            Some(argument) => match argument.parse::<f64>() {
-                Ok(interval) => Some(OutputOptions::Stdout(interval)),
-                Err(_) => match ServoUrl::parse(&argument) {
-                    Ok(_) => panic!("influxDB isn't supported anymore"),
-                    Err(_) => Some(OutputOptions::FileName(argument)),
-                },
-            },
-            None => Some(OutputOptions::Stdout(5.0)),
-        }
-    } else {
-        // if the p option doesn't exist:
-        None
-    };
-
-    if let Some(ref time_profiler_trace_path) = opt_match.opt_str("profiler-trace-path") {
-        let mut path = PathBuf::from(time_profiler_trace_path);
-        path.pop();
-        if let Err(why) = fs::create_dir_all(&path) {
-            error!(
-                "Couldn't create/open {:?}: {:?}",
-                Path::new(time_profiler_trace_path).to_string_lossy(),
-                why
-            );
-        }
-    }
-
-    let mem_profiler_period = opt_match.opt_default("m", "5").map(|period| {
-        period
-            .parse()
-            .unwrap_or_else(|err| args_fail(&format!("Error parsing option: -m ({})", err)))
-    });
-
-    let mut layout_threads: Option<usize> = opt_match.opt_str("y").map(|layout_threads_str| {
-        layout_threads_str
-            .parse()
-            .unwrap_or_else(|err| args_fail(&format!("Error parsing option: -y ({})", err)))
-    });
-
-    let nonincremental_layout = opt_match.opt_present("i");
-
-    let random_pipeline_closure_probability = opt_match
-        .opt_str("random-pipeline-closure-probability")
-        .map(|prob| {
-            prob.parse().unwrap_or_else(|err| {
-                args_fail(&format!(
-                    "Error parsing option: --random-pipeline-closure-probability ({})",
-                    err
-                ))
-            })
-        });
-
-    let random_pipeline_closure_seed =
-        opt_match
-            .opt_str("random-pipeline-closure-seed")
-            .map(|seed| {
-                seed.parse().unwrap_or_else(|err| {
-                    args_fail(&format!(
-                        "Error parsing option: --random-pipeline-closure-seed ({})",
-                        err
-                    ))
-                })
-            });
-
-    if debug_options.trace_layout {
-        layout_threads = Some(1);
-    }
-
-    let (devtools_server_enabled, devtools_port) = if opt_match.opt_present("devtools") {
-        let port = opt_match
-            .opt_str("devtools")
-            .map(|port| {
-                port.parse().unwrap_or_else(|err| {
-                    args_fail(&format!("Error parsing option: --devtools ({})", err))
-                })
-            })
-            .unwrap_or(pref!(devtools.server.port));
-        (true, port as u16)
-    } else {
-        (
-            pref!(devtools.server.enabled),
-            pref!(devtools.server.port) as u16,
-        )
-    };
-
-    let webdriver_port = opt_match.opt_default("webdriver", "7000").map(|port| {
-        port.parse().unwrap_or_else(|err| {
-            args_fail(&format!("Error parsing option: --webdriver ({})", err))
-        })
-    });
-
-    let parse_resolution_string = |string: String| {
-        let components: Vec<u32> = string
-            .split('x')
-            .map(|component| {
-                component.parse().unwrap_or_else(|error| {
-                    args_fail(&format!("Error parsing resolution '{string}': {error}"));
-                })
-            })
-            .collect();
-        Size2D::new(components[0], components[1])
-    };
-
-    let screen_size_override = opt_match
-        .opt_str("screen-size")
-        .map(parse_resolution_string);
-
-    // Make sure the default window size is not larger than any provided screen size.
-    let default_window_size = Size2D::new(1024, 740);
-    let default_window_size = screen_size_override
-        .map_or(default_window_size, |screen_size_override| {
-            default_window_size.min(screen_size_override)
-        });
-
-    let initial_window_size = opt_match
-        .opt_str("window-size")
-        .map_or(default_window_size, parse_resolution_string);
-
-    if opt_match.opt_present("M") {
-        MULTIPROCESS.store(true, Ordering::SeqCst)
-    }
-
-    let user_stylesheets = opt_match
-        .opt_strs("user-stylesheet")
-        .iter()
-        .map(|filename| {
-            let cwd = env::current_dir().unwrap();
-            let path = cwd.join(filename);
-            let url = ServoUrl::from_url(Url::from_file_path(&path).unwrap());
-            let mut contents = Vec::new();
-            File::open(path)
-                .unwrap_or_else(|err| args_fail(&format!("Couldn't open {}: {}", filename, err)))
-                .read_to_end(&mut contents)
-                .unwrap_or_else(|err| args_fail(&format!("Couldn't read {}: {}", filename, err)));
-            (contents, url)
-        })
-        .collect();
-
-    let is_printing_version = opt_match.opt_present("v") || opt_match.opt_present("version");
-
-    let legacy_layout = opt_match.opt_present("legacy-layout");
-    if legacy_layout {
-        set_pref!(layout.legacy_layout, true);
-    }
-
-    let opts = Opts {
-        debug: debug_options.clone(),
-        legacy_layout,
-        tile_size,
-        time_profiling,
-        time_profiler_trace_path: opt_match.opt_str("profiler-trace-path"),
-        mem_profiler_period,
-        nonincremental_layout,
-        userscripts: opt_match.opt_default("userscripts", ""),
-        user_stylesheets,
-        output_file: opt_match.opt_str("o"),
-        headless: opt_match.opt_present("z"),
-        hard_fail: opt_match.opt_present("f") && !opt_match.opt_present("F"),
-        devtools_port,
-        devtools_server_enabled,
-        webdriver_port,
-        initial_window_size,
-        screen_size_override,
-        multiprocess: opt_match.opt_present("M"),
-        background_hang_monitor: opt_match.opt_present("B"),
-        sandbox: opt_match.opt_present("S"),
-        random_pipeline_closure_probability,
-        random_pipeline_closure_seed,
-        exit_after_load: opt_match.opt_present("x"),
-        config_dir: opt_match.opt_str("config-dir").map(Into::into),
-        is_printing_version,
-        shaders_dir: opt_match.opt_str("shaders").map(Into::into),
-        certificate_path: opt_match.opt_str("certificate-path"),
-        ignore_certificate_errors: opt_match.opt_present("ignore-certificate-errors"),
-        unminify_js: opt_match.opt_present("unminify-js"),
-        local_script_source: opt_match.opt_str("local-script-source"),
-        unminify_css: opt_match.opt_present("unminify-css"),
-        print_pwm: opt_match.opt_present("print-pwm"),
-    };
-
-    set_options(opts);
-
-    if let Some(layout_threads) = layout_threads {
-        set_pref!(layout.threads, layout_threads as i64);
-    }
-
-    ArgumentParsingResult::ChromeProcess(opt_match)
-}
-
-pub enum ArgumentParsingResult {
-    ChromeProcess(Matches),
-    ContentProcess(Matches, String),
-}
-
 // Make Opts available globally. This saves having to clone and pass
 // opts everywhere it is used, which gets particularly cumbersome
 // when passing through the DOM structures.
 static OPTIONS: LazyLock<RwLock<Opts>> = LazyLock::new(|| RwLock::new(default_opts()));
 
 pub fn set_options(opts: Opts) {
-    MULTIPROCESS.store(opts.multiprocess, Ordering::SeqCst);
     *OPTIONS.write().unwrap() = opts;
 }
 
diff --git a/components/config/pref_util.rs b/components/config/pref_util.rs
index 4499cd89d37..47598206e05 100644
--- a/components/config/pref_util.rs
+++ b/components/config/pref_util.rs
@@ -2,11 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use std::collections::HashMap;
-use std::fmt;
-use std::str::FromStr;
-use std::sync::RwLock;
-
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
 
@@ -17,70 +12,46 @@ pub enum PrefValue {
     Str(String),
     Bool(bool),
     Array(Vec<PrefValue>),
-    Missing,
 }
 
 impl PrefValue {
-    pub fn as_str(&self) -> Option<&str> {
-        if let PrefValue::Str(val) = self {
-            Some(val)
-        } else {
-            None
-        }
-    }
-
-    pub fn as_i64(&self) -> Option<i64> {
-        if let PrefValue::Int(val) = self {
-            Some(*val)
-        } else {
-            None
-        }
-    }
-
-    pub fn as_f64(&self) -> Option<f64> {
-        if let PrefValue::Float(val) = self {
-            Some(*val)
-        } else {
-            None
-        }
-    }
-
-    pub fn as_bool(&self) -> Option<bool> {
-        if let PrefValue::Bool(val) = self {
-            Some(*val)
-        } else {
-            None
+    pub fn from_booleanish_str(input: &str) -> Self {
+        match input {
+            "false" => PrefValue::Bool(false),
+            "true" => PrefValue::Bool(true),
+            _ => input
+                .parse::<i64>()
+                .map(PrefValue::Int)
+                .or_else(|_| input.parse::<f64>().map(PrefValue::Float))
+                .unwrap_or_else(|_| PrefValue::from(input)),
         }
     }
+}
 
-    pub fn is_missing(&self) -> bool {
-        matches!(self, PrefValue::Missing)
-    }
+impl TryFrom<&Value> for PrefValue {
+    type Error = String;
 
-    pub fn from_json_value(value: &Value) -> Option<Self> {
+    fn try_from(value: &Value) -> Result<Self, Self::Error> {
         match value {
-            Value::Bool(b) => Some(PrefValue::Bool(*b)),
-            Value::Number(n) if n.is_i64() => Some(PrefValue::Int(n.as_i64().unwrap())),
-            Value::Number(n) if n.is_f64() => Some(PrefValue::Float(n.as_f64().unwrap())),
-            Value::String(s) => Some(PrefValue::Str(s.to_owned())),
-            _ => None,
-        }
-    }
-}
-
-impl FromStr for PrefValue {
-    type Err = PrefError;
-    fn from_str(s: &str) -> Result<Self, Self::Err> {
-        if s == "false" {
-            Ok(PrefValue::Bool(false))
-        } else if s == "true" {
-            Ok(PrefValue::Bool(true))
-        } else if let Ok(float) = s.parse::<f64>() {
-            Ok(PrefValue::Float(float))
-        } else if let Ok(integer) = s.parse::<i64>() {
-            Ok(PrefValue::Int(integer))
-        } else {
-            Ok(PrefValue::from(s))
+            Value::Null => Err("Cannot turn null into preference".into()),
+            Value::Bool(value) => Ok((*value).into()),
+            Value::Number(number) => number
+                .as_i64()
+                .map(Into::into)
+                .or_else(|| number.as_f64().map(Into::into))
+                .map(Ok)
+                .unwrap_or(Err("Could not parse number from JSON".into())),
+            Value::String(value) => Ok(value.clone().into()),
+            Value::Array(array) => {
+                let mut array = array.iter().map(TryInto::try_into);
+                if !array.all(|v| v.is_ok()) {
+                    return Err(format!(
+                        "Cannot turn all array avlues into preference: {array:?}"
+                    ));
+                }
+                Ok(PrefValue::Array(array.map(Result::unwrap).collect()))
+            },
+            Value::Object(_) => Err("Cannot turn object into preference".into()),
         }
     }
 }
@@ -94,37 +65,18 @@ macro_rules! impl_pref_from {
                 }
             }
         )+
-        $(
-            impl From<Option<$t>> for PrefValue {
-                fn from(other: Option<$t>) -> Self {
-                    other.map(|val| $variant(val.into())).unwrap_or(PrefValue::Missing)
-                }
-            }
-        )+
     }
 }
 
 macro_rules! impl_from_pref {
     ($($variant: path => $t: ty,)*) => {
         $(
-            impl From<PrefValue> for $t {
-                #[allow(unsafe_code)]
-                fn from(other: PrefValue) -> Self {
-                    if let $variant(value) = other {
-                        value.into()
-                    } else {
-                        panic!("Cannot convert {:?} to {:?}", other, std::any::type_name::<$t>())
-                    }
-                }
-            }
-        )+
-        $(
-            impl From<PrefValue> for Option<$t> {
-                fn from(other: PrefValue) -> Self {
-                    if let PrefValue::Missing = other {
-                        None
-                    } else {
-                        Some(other.into())
+            impl TryFrom<PrefValue> for $t {
+                type Error = String;
+                fn try_from(other: PrefValue) -> Result<Self, Self::Error> {
+                    match other {
+                        $variant(value) => Ok(value.into()),
+                        _ => Err(format!("Cannot convert {other:?} to {}", std::any::type_name::<$t>())),
                     }
                 }
             }
@@ -157,9 +109,13 @@ impl From<PrefValue> for [f64; 4] {
     fn from(other: PrefValue) -> [f64; 4] {
         match other {
             PrefValue::Array(values) if values.len() == 4 => {
-                let f = values.into_iter().map(Into::into).collect::<Vec<f64>>();
-                if f.len() == 4 {
-                    [f[0], f[1], f[2], f[3]]
+                let values: Vec<f64> = values
+                    .into_iter()
+                    .map(TryFrom::try_from)
+                    .filter_map(Result::ok)
+                    .collect();
+                if values.len() == 4 {
+                    [values[0], values[1], values[2], values[3]]
                 } else {
                     panic!(
                         "Cannot convert PrefValue to {:?}",
@@ -176,144 +132,20 @@ impl From<PrefValue> for [f64; 4] {
     }
 }
 
-#[derive(Debug)]
-pub enum PrefError {
-    NoSuchPref(String),
-    InvalidValue(String),
-    JsonParseErr(serde_json::error::Error),
-}
+#[test]
+fn test_pref_value_from_str() {
+    let value = PrefValue::from_booleanish_str("21");
+    assert_eq!(value, PrefValue::Int(21));
 
-impl fmt::Display for PrefError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match self {
-            PrefError::NoSuchPref(s) | PrefError::InvalidValue(s) => f.write_str(s),
-            PrefError::JsonParseErr(e) => e.fmt(f),
-        }
-    }
-}
+    let value = PrefValue::from_booleanish_str("12.5");
+    assert_eq!(value, PrefValue::Float(12.5));
 
-impl std::error::Error for PrefError {}
+    let value = PrefValue::from_booleanish_str("a string");
+    assert_eq!(value, PrefValue::Str("a string".into()));
 
-pub struct Accessor<P, V> {
-    pub getter: Box<dyn Fn(&P) -> V + Sync + Send>,
-    #[allow(clippy::type_complexity)]
-    pub setter: Box<dyn Fn(&mut P, V) + Sync + Send>,
-}
+    let value = PrefValue::from_booleanish_str("false");
+    assert_eq!(value, PrefValue::Bool(false));
 
-impl<P, V> Accessor<P, V> {
-    pub fn new<G, S>(getter: G, setter: S) -> Self
-    where
-        G: Fn(&P) -> V + Sync + Send + 'static,
-        S: Fn(&mut P, V) + Sync + Send + 'static,
-    {
-        Accessor {
-            getter: Box::new(getter),
-            setter: Box::new(setter),
-        }
-    }
-}
-
-pub struct Preferences<'m, P> {
-    user_prefs: RwLock<P>,
-    default_prefs: P,
-    accessors: &'m HashMap<String, Accessor<P, PrefValue>>,
-}
-
-impl<'m, P: Clone> Preferences<'m, P> {
-    /// Create a new `Preferences` object. The values provided in `default_prefs` are immutable and
-    /// can always be restored using `reset` or `reset_all`.
-    pub fn new(default_prefs: P, accessors: &'m HashMap<String, Accessor<P, PrefValue>>) -> Self {
-        Self {
-            user_prefs: RwLock::new(default_prefs.clone()),
-            default_prefs,
-            accessors,
-        }
-    }
-
-    /// Access to the data structure holding the preference values.
-    pub fn values(&self) -> &RwLock<P> {
-        &self.user_prefs
-    }
-
-    /// Retrieve a preference using its key
-    pub fn get(&self, key: &str) -> PrefValue {
-        if let Some(accessor) = self.accessors.get(key) {
-            let prefs = self.user_prefs.read().unwrap();
-            (accessor.getter)(&prefs)
-        } else {
-            PrefValue::Missing
-        }
-    }
-
-    /// Has the preference been modified from its original value?
-    pub fn is_default(&self, key: &str) -> Result<bool, PrefError> {
-        if let Some(accessor) = self.accessors.get(key) {
-            let user = (accessor.getter)(&self.default_prefs);
-            let default = (accessor.getter)(&self.user_prefs.read().unwrap());
-            Ok(default == user)
-        } else {
-            Err(PrefError::NoSuchPref(String::from(key)))
-        }
-    }
-
-    /// Creates an iterator over all keys and values
-    pub fn iter(&self) -> impl Iterator<Item = (String, PrefValue)> + '_ {
-        let prefs = self.user_prefs.read().unwrap();
-        self.accessors
-            .iter()
-            .map(move |(k, accessor)| (k.clone(), (accessor.getter)(&prefs)))
-    }
-
-    /// Creates an iterator over all keys
-    pub fn keys(&self) -> impl Iterator<Item = &'_ str> {
-        self.accessors.keys().map(String::as_str)
-    }
-
-    fn set_inner<V>(&self, key: &str, prefs: &mut P, val: V) -> Result<(), PrefError>
-    where
-        V: Into<PrefValue>,
-    {
-        if let Some(accessor) = self.accessors.get(key) {
-            (accessor.setter)(prefs, val.into());
-            Ok(())
-        } else {
-            Err(PrefError::NoSuchPref(String::from(key)))
-        }
-    }
-
-    /// Set a new value for a preference, using its key.
-    pub fn set<V>(&self, key: &str, val: V) -> Result<(), PrefError>
-    where
-        V: Into<PrefValue>,
-    {
-        let mut prefs = self.user_prefs.write().unwrap();
-        self.set_inner(key, &mut prefs, val)
-    }
-
-    pub fn set_all<M>(&self, values: M) -> Result<(), PrefError>
-    where
-        M: IntoIterator<Item = (String, PrefValue)>,
-    {
-        let mut prefs = self.user_prefs.write().unwrap();
-        for (k, v) in values.into_iter() {
-            self.set_inner(&k, &mut prefs, v)?;
-        }
-        Ok(())
-    }
-
-    pub fn reset(&self, key: &str) -> Result<PrefValue, PrefError> {
-        if let Some(accessor) = self.accessors.get(key) {
-            let mut prefs = self.user_prefs.write().unwrap();
-            let old_pref = (accessor.getter)(&prefs);
-            let default_pref = (accessor.getter)(&self.default_prefs);
-            (accessor.setter)(&mut prefs, default_pref);
-            Ok(old_pref)
-        } else {
-            Err(PrefError::NoSuchPref(String::from(key)))
-        }
-    }
-
-    pub fn reset_all(&self) {
-        *self.user_prefs.write().unwrap() = self.default_prefs.clone();
-    }
+    let value = PrefValue::from_booleanish_str("true");
+    assert_eq!(value, PrefValue::Bool(true));
 }
diff --git a/components/config/prefs.rs b/components/config/prefs.rs
index 87eea9a1cc0..9c4edf30e3a 100644
--- a/components/config/prefs.rs
+++ b/components/config/prefs.rs
@@ -2,659 +2,386 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use std::borrow::ToOwned;
-use std::collections::HashMap;
-use std::convert::{TryFrom, TryInto};
-use std::sync::LazyLock;
+use std::sync::{RwLock, RwLockReadGuard};
 
-use embedder_traits::resources::{self, Resource};
-use gen::Prefs;
-use log::{error, warn};
-use serde_json::{self, Value};
+use serde::{Deserialize, Serialize};
+use servo_config_macro::ServoPreferences;
 
-use crate::pref_util::Preferences;
-pub use crate::pref_util::{PrefError, PrefValue};
+pub use crate::pref_util::PrefValue;
 
-static PREFS: LazyLock<Preferences<'static, Prefs>> = LazyLock::new(|| {
-    let def_prefs: Prefs = serde_json::from_str(&resources::read_string(Resource::Preferences))
-        .unwrap_or_else(|_| {
-            error!("Preference json file is invalid. Setting Preference to default values");
-            Prefs::default()
-        });
-    let result = Preferences::new(def_prefs, &gen::PREF_ACCESSORS);
-    for (key, value) in result.iter() {
-        set_stylo_pref_ref(&key, &value);
-    }
-    result
-});
-
-/// A convenience macro for accessing a preference value using its static path.
-/// Passing an invalid path is a compile-time error.
-#[macro_export]
-macro_rules! pref {
-    ($($segment: ident).+) => {{
-        let values = $crate::prefs::pref_map().values();
-        let lock = values.read()
-            .map(|prefs| prefs $(.$segment)+.clone());
-        lock.unwrap()
-    }};
-}
-
-/// A convenience macro for updating a preference value using its static path.
-/// Passing an invalid path is a compile-time error.
-#[macro_export]
-macro_rules! set_pref {
-    ($($segment: ident).+, $value: expr) => {{
-        let value = $value;
-        $crate::prefs::set_stylo_pref(stringify!($($segment).+), value);
-        let values = $crate::prefs::pref_map().values();
-        let mut lock = values.write().unwrap();
-        lock$ (.$segment)+ = value;
-    }};
-}
+static PREFERENCES: RwLock<Preferences> = RwLock::new(Preferences::new());
 
-/// Access preferences using their `String` keys. Note that the key may be different from the
-/// static path because legacy keys contain hyphens, or because a preference name has been renamed.
-///
-/// When retrieving a preference, the value will always be a `PrefValue`. When setting a value, it
-/// may be a `PrefValue` or the type that converts into the correct underlying value; one of `bool`,
-/// `i64`, `f64` or `String`.
 #[inline]
-pub fn pref_map() -> &'static Preferences<'static, Prefs> {
-    &PREFS
-}
-
-pub fn add_user_prefs(prefs: HashMap<String, PrefValue>) {
-    for (key, value) in prefs.iter() {
-        set_stylo_pref_ref(key, value);
-    }
-    if let Err(error) = PREFS.set_all(prefs) {
-        panic!("Error setting preference: {:?}", error);
-    }
+/// Get the current set of global preferences for Servo.
+pub fn get() -> RwLockReadGuard<'static, Preferences> {
+    PREFERENCES.read().unwrap()
 }
 
-pub fn set_stylo_pref(key: &str, value: impl Into<PrefValue>) {
-    set_stylo_pref_ref(key, &value.into());
-}
+pub fn set(preferences: Preferences) {
+    // Map between Stylo preference names and Servo preference names as the This should be
+    // kept in sync with components/script/dom/bindings/codegen/run.py which generates the
+    // DOM CSS style accessors.
+    style_config::set_bool("layout.unimplemented", preferences.layout_unimplemented);
+    style_config::set_i32("layout.threads", preferences.layout_threads as i32);
+    style_config::set_bool("layout.legacy_layout", preferences.layout_legacy_layout);
+    style_config::set_bool("layout.flexbox.enabled", preferences.layout_flexbox_enabled);
+    style_config::set_bool("layout.columns.enabled", preferences.layout_columns_enabled);
+    style_config::set_bool("layout.grid.enabled", preferences.layout_grid_enabled);
+    style_config::set_bool(
+        "layout.css.transition-behavior.enabled",
+        preferences.layout_css_transition_behavior_enabled,
+    );
+    style_config::set_bool(
+        "layout.writing-mode.enabled",
+        preferences.layout_writing_mode_enabled,
+    );
+    style_config::set_bool(
+        "layout.container-queries.enabled",
+        preferences.layout_container_queries_enabled,
+    );
 
-fn set_stylo_pref_ref(key: &str, value: &PrefValue) {
-    match value.try_into() {
-        Ok(StyloPrefValue::Bool(value)) => style_config::set_bool(key, value),
-        Ok(StyloPrefValue::Int(value)) => style_config::set_i32(key, value),
-        Err(TryFromPrefValueError::IntegerOverflow(value)) => {
-            // TODO: logging doesn’t actually work this early, so we should
-            // split PrefValue into i32 and i64 variants.
-            warn!("Pref value too big for Stylo: {} ({})", key, value);
-        },
-        Err(TryFromPrefValueError::UnmappedType) => {
-            // Most of Servo’s prefs will hit this. When adding a new pref type
-            // in Stylo, update TryFrom<&PrefValue> for StyloPrefValue as well.
-        },
-    }
+    *PREFERENCES.write().unwrap() = preferences;
 }
 
-enum StyloPrefValue {
-    Bool(bool),
-    Int(i32),
+/// A convenience macro for accessing a preference value using its static path.
+/// Passing an invalid path is a compile-time error.
+#[macro_export]
+macro_rules! pref {
+    ($name: ident) => {
+        $crate::prefs::get().$name.clone()
+    };
 }
 
-enum TryFromPrefValueError {
-    IntegerOverflow(i64),
-    UnmappedType,
+#[derive(Clone, Deserialize, Serialize, ServoPreferences)]
+pub struct Preferences {
+    pub fonts_default: String,
+    pub fonts_serif: String,
+    pub fonts_sans_serif: String,
+    pub fonts_monospace: String,
+    pub fonts_default_size: i64,
+    pub fonts_default_monospace_size: i64,
+    pub css_animations_testing_enabled: bool,
+    /// Start the devtools server at startup
+    pub devtools_server_enabled: bool,
+    /// Port number to start a server to listen to remote Firefox devtools connections.
+    /// 0 for random port.
+    pub devtools_server_port: i64,
+    pub dom_webgpu_enabled: bool,
+    /// List of comma-separated backends to be used by wgpu.
+    pub dom_webgpu_wgpu_backend: String,
+    pub dom_abort_controller_enabled: bool,
+    pub dom_bluetooth_enabled: bool,
+    pub dom_bluetooth_testing_enabled: bool,
+    pub dom_allow_scripts_to_close_windows: bool,
+    pub dom_canvas_capture_enabled: bool,
+    pub dom_canvas_text_enabled: bool,
+    pub dom_composition_event_enabled: bool,
+    pub dom_crypto_subtle_enabled: bool,
+    pub dom_customelements_enabled: bool,
+    pub dom_document_dblclick_timeout: i64,
+    pub dom_document_dblclick_dist: i64,
+    pub dom_forcetouch_enabled: bool,
+    pub dom_fullscreen_test: bool,
+    pub dom_gamepad_enabled: bool,
+    pub dom_imagebitmap_enabled: bool,
+    pub dom_intersection_observer_enabled: bool,
+    pub dom_microdata_testing_enabled: bool,
+    pub dom_mouse_event_which_enabled: bool,
+    pub dom_mutation_observer_enabled: bool,
+    pub dom_offscreen_canvas_enabled: bool,
+    pub dom_permissions_enabled: bool,
+    pub dom_permissions_testing_allowed_in_nonsecure_contexts: bool,
+    pub dom_resize_observer_enabled: bool,
+    pub dom_script_asynch: bool,
+    pub dom_serviceworker_enabled: bool,
+    pub dom_serviceworker_timeout_seconds: i64,
+    pub dom_servo_helpers_enabled: bool,
+    pub dom_servoparser_async_html_tokenizer_enabled: bool,
+    pub dom_shadowdom_enabled: bool,
+    pub dom_svg_enabled: bool,
+    pub dom_testable_crash_enabled: bool,
+    pub dom_testbinding_enabled: bool,
+    pub dom_testbinding_prefcontrolled_enabled: bool,
+    pub dom_testbinding_prefcontrolled2_enabled: bool,
+    pub dom_testbinding_preference_value_falsy: bool,
+    pub dom_testbinding_preference_value_quote_string_test: String,
+    pub dom_testbinding_preference_value_space_string_test: String,
+    pub dom_testbinding_preference_value_string_empty: String,
+    pub dom_testbinding_preference_value_string_test: String,
+    pub dom_testbinding_preference_value_truthy: bool,
+    pub dom_testing_element_activation_enabled: bool,
+    pub dom_testing_html_input_element_select_files_enabled: bool,
+    pub dom_testperf_enabled: bool,
+    pub dom_xpath_enabled: bool,
+    /// Enable WebGL2 APIs.
+    pub dom_webgl2_enabled: bool,
+    pub dom_webrtc_enabled: bool,
+    pub dom_webrtc_transceiver_enabled: bool,
+    pub dom_webvtt_enabled: bool,
+    pub dom_webxr_enabled: bool,
+    pub dom_webxr_test: bool,
+    pub dom_webxr_first_person_observer_view: bool,
+    pub dom_webxr_glwindow_enabled: bool,
+    pub dom_webxr_glwindow_left_right: bool,
+    pub dom_webxr_glwindow_red_cyan: bool,
+    pub dom_webxr_glwindow_spherical: bool,
+    pub dom_webxr_glwindow_cubemap: bool,
+    pub dom_webxr_hands_enabled: bool,
+    pub dom_webxr_layers_enabled: bool,
+    pub dom_webxr_openxr_enabled: bool,
+    pub dom_webxr_sessionavailable: bool,
+    pub dom_webxr_unsafe_assume_user_intent: bool,
+    pub dom_worklet_enabled: bool,
+    pub dom_worklet_blockingsleep: bool,
+    pub dom_worklet_testing_enabled: bool,
+    pub dom_worklet_timeout_ms: i64,
+    pub gfx_subpixel_text_antialiasing_enabled: bool,
+    pub gfx_texture_swizzling_enabled: bool,
+    pub js_asmjs_enabled: bool,
+    pub js_asyncstack: bool,
+    pub js_baseline_interpreter_enabled: bool,
+    /// Whether to disable the jit within SpiderMonkey
+    pub js_disable_jit: bool,
+    pub js_baseline_jit_enabled: bool,
+    pub js_baseline_jit_unsafe_eager_compilation_enabled: bool,
+    pub js_discard_system_source: bool,
+    pub js_dump_stack_on_debuggee_would_run: bool,
+    pub js_ion_enabled: bool,
+    pub js_ion_offthread_compilation_enabled: bool,
+    pub js_ion_unsafe_eager_compilation_enabled: bool,
+    pub js_mem_gc_allocation_threshold_mb: i64,
+    pub js_mem_gc_allocation_threshold_factor: i64,
+    pub js_mem_gc_allocation_threshold_avoid_interrupt_factor: i64,
+    pub js_mem_gc_compacting_enabled: bool,
+    pub js_mem_gc_decommit_threshold_mb: i64,
+    pub js_mem_gc_dynamic_heap_growth_enabled: bool,
+    pub js_mem_gc_dynamic_mark_slice_enabled: bool,
+    pub js_mem_gc_empty_chunk_count_max: i64,
+    pub js_mem_gc_empty_chunk_count_min: i64,
+    pub js_mem_gc_high_frequency_heap_growth_max: i64,
+    pub js_mem_gc_high_frequency_heap_growth_min: i64,
+    pub js_mem_gc_high_frequency_high_limit_mb: i64,
+    pub js_mem_gc_high_frequency_low_limit_mb: i64,
+    pub js_mem_gc_high_frequency_time_limit_ms: i64,
+    pub js_mem_gc_incremental_enabled: bool,
+    pub js_mem_gc_incremental_slice_ms: i64,
+    pub js_mem_gc_low_frequency_heap_growth: i64,
+    pub js_mem_gc_per_zone_enabled: bool,
+    pub js_mem_gc_zeal_frequency: i64,
+    pub js_mem_gc_zeal_level: i64,
+    pub js_mem_max: i64,
+    pub js_native_regex_enabled: bool,
+    pub js_offthread_compilation_enabled: bool,
+    pub js_parallel_parsing_enabled: bool,
+    pub js_shared_memory: bool,
+    pub js_throw_on_asmjs_validation_failure: bool,
+    pub js_throw_on_debuggee_would_run: bool,
+    pub js_timers_minimum_duration: i64,
+    pub js_wasm_baseline_enabled: bool,
+    pub js_wasm_enabled: bool,
+    pub js_wasm_ion_enabled: bool,
+    pub js_werror_enabled: bool,
+    pub layout_animations_test_enabled: bool,
+    pub layout_columns_enabled: bool,
+    pub layout_grid_enabled: bool,
+    pub layout_container_queries_enabled: bool,
+    pub layout_css_transition_behavior_enabled: bool,
+    pub layout_flexbox_enabled: bool,
+    pub layout_legacy_layout: bool,
+    pub layout_threads: i64,
+    pub layout_unimplemented: bool,
+    pub layout_writing_mode_enabled: bool,
+    /// Enable hardware acceleration for video playback.
+    pub media_glvideo_enabled: bool,
+    /// Enable a non-standard event handler for verifying behavior of media elements during tests.
+    pub media_testing_enabled: bool,
+    pub network_enforce_tls_enabled: bool,
+    pub network_enforce_tls_localhost: bool,
+    pub network_enforce_tls_onion: bool,
+    pub network_http_cache_disabled: bool,
+    pub network_local_directory_listing_enabled: bool,
+    pub network_mime_sniff: bool,
+    /// Ignore `std::io::Error` with `ErrorKind::UnexpectedEof` received when a TLS connection
+    /// is closed without a close_notify.
+    ///
+    /// Used for tests because WPT server doesn't properly close the TLS connection.
+    // TODO: remove this when WPT server is updated to use a proper TLS implementation.
+    pub network_tls_ignore_unexpected_eof: bool,
+    pub session_history_max_length: i64,
+    /// The background color of shell's viewport. This will be used by OpenGL's `glClearColor`.
+    pub shell_background_color_rgba: [f64; 4],
+    pub webgl_testing_context_creation_error: bool,
+    /// Number of workers per threadpool, if we fail to detect how much
+    /// parallelism is available at runtime.
+    pub threadpools_fallback_worker_num: i64,
+    /// Maximum number of workers for the Image Cache thread pool
+    pub threadpools_image_cache_workers_max: i64,
+    /// Maximum number of workers for the Networking async runtime thread pool
+    pub threadpools_async_runtime_workers_max: i64,
+    /// Maximum number of workers for the Core Resource Manager
+    pub threadpools_resource_workers_max: i64,
+    /// Maximum number of workers for webrender
+    pub threadpools_webrender_workers_max: i64,
 }
 
-impl TryFrom<&PrefValue> for StyloPrefValue {
-    type Error = TryFromPrefValueError;
-
-    fn try_from(value: &PrefValue) -> Result<Self, Self::Error> {
-        match *value {
-            PrefValue::Int(value) => {
-                if let Ok(value) = value.try_into() {
-                    Ok(Self::Int(value))
-                } else {
-                    Err(TryFromPrefValueError::IntegerOverflow(value))
-                }
-            },
-            PrefValue::Bool(value) => Ok(Self::Bool(value)),
-            _ => Err(TryFromPrefValueError::UnmappedType),
+impl Preferences {
+    const fn new() -> Self {
+        Self {
+            css_animations_testing_enabled: false,
+            devtools_server_enabled: false,
+            devtools_server_port: 0,
+            dom_abort_controller_enabled: false,
+            dom_allow_scripts_to_close_windows: false,
+            dom_bluetooth_enabled: false,
+            dom_bluetooth_testing_enabled: false,
+            dom_canvas_capture_enabled: false,
+            dom_canvas_text_enabled: true,
+            dom_composition_event_enabled: false,
+            dom_crypto_subtle_enabled: true,
+            dom_customelements_enabled: true,
+            dom_document_dblclick_dist: 1,
+            dom_document_dblclick_timeout: 300,
+            dom_forcetouch_enabled: false,
+            dom_fullscreen_test: false,
+            dom_gamepad_enabled: true,
+            dom_imagebitmap_enabled: false,
+            dom_intersection_observer_enabled: false,
+            dom_microdata_testing_enabled: false,
+            dom_mouse_event_which_enabled: false,
+            dom_mutation_observer_enabled: true,
+            dom_offscreen_canvas_enabled: false,
+            dom_permissions_enabled: false,
+            dom_permissions_testing_allowed_in_nonsecure_contexts: false,
+            dom_resize_observer_enabled: false,
+            dom_script_asynch: true,
+            dom_serviceworker_enabled: false,
+            dom_serviceworker_timeout_seconds: 60,
+            dom_servo_helpers_enabled: false,
+            dom_servoparser_async_html_tokenizer_enabled: false,
+            dom_shadowdom_enabled: false,
+            dom_svg_enabled: false,
+            dom_testable_crash_enabled: false,
+            dom_testbinding_enabled: false,
+            dom_testbinding_prefcontrolled2_enabled: false,
+            dom_testbinding_prefcontrolled_enabled: false,
+            dom_testbinding_preference_value_falsy: false,
+            dom_testbinding_preference_value_quote_string_test: String::new(),
+            dom_testbinding_preference_value_space_string_test: String::new(),
+            dom_testbinding_preference_value_string_empty: String::new(),
+            dom_testbinding_preference_value_string_test: String::new(),
+            dom_testbinding_preference_value_truthy: false,
+            dom_testing_element_activation_enabled: false,
+            dom_testing_html_input_element_select_files_enabled: false,
+            dom_testperf_enabled: false,
+            dom_webgl2_enabled: false,
+            dom_webgpu_enabled: false,
+            dom_webgpu_wgpu_backend: String::new(),
+            dom_webrtc_enabled: false,
+            dom_webrtc_transceiver_enabled: false,
+            dom_webvtt_enabled: false,
+            dom_webxr_enabled: true,
+            dom_webxr_first_person_observer_view: false,
+            dom_webxr_glwindow_cubemap: false,
+            dom_webxr_glwindow_enabled: true,
+            dom_webxr_glwindow_left_right: false,
+            dom_webxr_glwindow_red_cyan: false,
+            dom_webxr_glwindow_spherical: false,
+            dom_webxr_hands_enabled: true,
+            dom_webxr_layers_enabled: false,
+            dom_webxr_openxr_enabled: true,
+            dom_webxr_sessionavailable: false,
+            dom_webxr_test: false,
+            dom_webxr_unsafe_assume_user_intent: false,
+            dom_worklet_blockingsleep: false,
+            dom_worklet_enabled: false,
+            dom_worklet_testing_enabled: false,
+            dom_worklet_timeout_ms: 10,
+            dom_xpath_enabled: false,
+            fonts_default: String::new(),
+            fonts_default_monospace_size: 13,
+            fonts_default_size: 16,
+            fonts_monospace: String::new(),
+            fonts_sans_serif: String::new(),
+            fonts_serif: String::new(),
+            gfx_subpixel_text_antialiasing_enabled: true,
+            gfx_texture_swizzling_enabled: true,
+            js_asmjs_enabled: true,
+            js_asyncstack: false,
+            js_baseline_interpreter_enabled: true,
+            js_baseline_jit_enabled: true,
+            js_baseline_jit_unsafe_eager_compilation_enabled: false,
+            js_disable_jit: false,
+            js_discard_system_source: false,
+            js_dump_stack_on_debuggee_would_run: false,
+            js_ion_enabled: true,
+            js_ion_offthread_compilation_enabled: true,
+            js_ion_unsafe_eager_compilation_enabled: false,
+            js_mem_gc_allocation_threshold_avoid_interrupt_factor: 100,
+            js_mem_gc_allocation_threshold_factor: 100,
+            js_mem_gc_allocation_threshold_mb: 30,
+            js_mem_gc_compacting_enabled: true,
+            js_mem_gc_decommit_threshold_mb: 32,
+            js_mem_gc_dynamic_heap_growth_enabled: true,
+            js_mem_gc_dynamic_mark_slice_enabled: true,
+            js_mem_gc_empty_chunk_count_max: 30,
+            js_mem_gc_empty_chunk_count_min: 1,
+            js_mem_gc_high_frequency_heap_growth_max: 300,
+            js_mem_gc_high_frequency_heap_growth_min: 150,
+            js_mem_gc_high_frequency_high_limit_mb: 500,
+            js_mem_gc_high_frequency_low_limit_mb: 100,
+            js_mem_gc_high_frequency_time_limit_ms: 1000,
+            js_mem_gc_incremental_enabled: true,
+            js_mem_gc_incremental_slice_ms: 10,
+            js_mem_gc_low_frequency_heap_growth: 150,
+            js_mem_gc_per_zone_enabled: false,
+            js_mem_gc_zeal_frequency: 100,
+            js_mem_gc_zeal_level: 0,
+            js_mem_max: -1,
+            js_native_regex_enabled: true,
+            js_offthread_compilation_enabled: true,
+            js_parallel_parsing_enabled: true,
+            js_shared_memory: true,
+            js_throw_on_asmjs_validation_failure: false,
+            js_throw_on_debuggee_would_run: false,
+            js_timers_minimum_duration: 1000,
+            js_wasm_baseline_enabled: true,
+            js_wasm_enabled: true,
+            js_wasm_ion_enabled: true,
+            js_werror_enabled: false,
+            layout_animations_test_enabled: false,
+            layout_columns_enabled: false,
+            layout_container_queries_enabled: false,
+            layout_css_transition_behavior_enabled: true,
+            layout_flexbox_enabled: true,
+            layout_grid_enabled: false,
+            layout_legacy_layout: false,
+            // TODO(mrobinson): This should likely be based on the number of processors.
+            layout_threads: 3,
+            layout_unimplemented: false,
+            layout_writing_mode_enabled: false,
+            media_glvideo_enabled: false,
+            media_testing_enabled: false,
+            network_enforce_tls_enabled: false,
+            network_enforce_tls_localhost: false,
+            network_enforce_tls_onion: false,
+            network_http_cache_disabled: false,
+            network_local_directory_listing_enabled: false,
+            network_mime_sniff: false,
+            network_tls_ignore_unexpected_eof: false,
+            session_history_max_length: 20,
+            shell_background_color_rgba: [1.0, 1.0, 1.0, 1.0],
+            threadpools_async_runtime_workers_max: 6,
+            threadpools_fallback_worker_num: 3,
+            threadpools_image_cache_workers_max: 4,
+            threadpools_resource_workers_max: 4,
+            threadpools_webrender_workers_max: 4,
+            webgl_testing_context_creation_error: false,
         }
     }
 }
 
-pub fn read_prefs_map(txt: &str) -> Result<HashMap<String, PrefValue>, PrefError> {
-    let prefs: HashMap<String, Value> =
-        serde_json::from_str(txt).map_err(PrefError::JsonParseErr)?;
-    prefs
-        .into_iter()
-        .map(|(k, pref_value)| {
-            Ok({
-                let v = match &pref_value {
-                    Value::Bool(b) => PrefValue::Bool(*b),
-                    Value::Number(n) if n.is_i64() => PrefValue::Int(n.as_i64().unwrap()),
-                    Value::Number(n) if n.is_f64() => PrefValue::Float(n.as_f64().unwrap()),
-                    Value::String(s) => PrefValue::Str(s.to_owned()),
-                    Value::Array(v) => {
-                        let mut array = v.iter().map(PrefValue::from_json_value);
-                        if array.all(|v| v.is_some()) {
-                            PrefValue::Array(array.flatten().collect())
-                        } else {
-                            return Err(PrefError::InvalidValue(format!(
-                                "Invalid value: {}",
-                                pref_value
-                            )));
-                        }
-                    },
-                    _ => {
-                        return Err(PrefError::InvalidValue(format!(
-                            "Invalid value: {}",
-                            pref_value
-                        )));
-                    },
-                };
-                (k.to_owned(), v)
-            })
-        })
-        .collect()
-}
-
-mod gen {
-    use serde::{Deserialize, Serialize};
-    use servo_config_plugins::build_structs;
-
-    // The number of layout threads is calculated if it is not present in `prefs.json`.
-    fn default_layout_threads() -> i64 {
-        std::cmp::max(num_cpus::get() * 3 / 4, 1) as i64
-    }
-
-    fn default_font_size() -> i64 {
-        16
-    }
-
-    fn default_monospace_font_size() -> i64 {
-        13
-    }
-
-    build_structs! {
-        // type of the accessors
-        accessor_type = crate::pref_util::Accessor::<Prefs, crate::pref_util::PrefValue>,
-        // name of the constant, which will hold a HashMap of preference accessors
-        gen_accessors = PREF_ACCESSORS,
-        // tree of structs to generate
-        gen_types = Prefs {
-            fonts: {
-                #[serde(default)]
-                default: String,
-                #[serde(default)]
-                serif: String,
-                #[serde(default)]
-                #[serde(rename = "fonts.sans-serif")]
-                sans_serif: String,
-                #[serde(default)]
-                monospace: String,
-                #[serde(default = "default_font_size")]
-                #[serde(rename = "fonts.default-size")]
-                default_size: i64,
-                #[serde(default = "default_monospace_font_size")]
-                #[serde(rename = "fonts.default-monospace-size")]
-                default_monospace_size: i64,
-            },
-            /// Allows customizing the different threadpools used by servo
-            threadpools: {
-                /// Number of workers per threadpool, if we fail to detect how much
-                /// parallelism is available at runtime.
-                fallback_worker_num: i64,
-                image_cache_workers: {
-                    /// Maximum number of workers for the Image Cache thread pool
-                    max: i64,
-                },
-                async_runtime_workers: {
-                    /// Maximum number of workers for the Networking async runtime thread pool
-                    max: i64
-                },
-                resource_workers: {
-                    /// Maximum number of workers for the Core Resource Manager
-                    max: i64,
-                },
-                webrender_workers: {
-                    /// Maximum number of workers for webrender
-                    max: i64,
-                },
-            },
-            css: {
-                animations: {
-                    testing: {
-                        #[serde(default)]
-                        enabled: bool,
-                    },
-                },
-            },
-            devtools: {
-                server: {
-                    enabled: bool,
-                    port: i64,
-                },
-            },
-            dom: {
-                webgpu: {
-                    /// Enable WebGPU APIs.
-                    enabled: bool,
-                    /// List of comma-separated backends to be used by wgpu
-                    wgpu_backend: String,
-                },
-                bluetooth: {
-                    enabled: bool,
-                    testing: {
-                        enabled: bool,
-                    }
-                },
-                abort_controller: {
-                    /// Whether to expose the AbortControll/AbortSignal DOM interfaces.
-                    enabled: bool,
-                },
-                allow_scripts_to_close_windows: bool,
-                canvas_capture: {
-                    enabled: bool,
-                },
-                canvas_text: {
-                    enabled: bool,
-                },
-                composition_event: {
-                    #[serde(rename = "dom.compositionevent.enabled")]
-                    enabled: bool,
-                },
-                crypto: {
-                    subtle: {
-                        enabled: bool,
-                    }
-                },
-                custom_elements: {
-                    #[serde(rename = "dom.customelements.enabled")]
-                    enabled: bool,
-                },
-                document: {
-                    dblclick_timeout: i64,
-                    dblclick_dist: i64,
-                },
-                forcetouch: {
-                    enabled: bool,
-                },
-                fullscreen: {
-                    test: bool,
-                },
-                gamepad: {
-                    enabled: bool,
-                },
-                imagebitmap: {
-                    enabled: bool,
-                },
-                intersection_observer: {
-                    enabled: bool,
-                },
-                microdata: {
-                    testing: {
-                        enabled: bool,
-                    }
-                },
-                mouse_event: {
-                    which: {
-                        #[serde(rename = "dom.mouseevent.which.enabled")]
-                        enabled: bool,
-                    }
-                },
-                mutation_observer: {
-                    enabled: bool,
-                },
-                offscreen_canvas: {
-                    enabled: bool,
-                },
-                permissions: {
-                    enabled: bool,
-                    testing: {
-                        allowed_in_nonsecure_contexts: bool,
-                    }
-                },
-                resize_observer: {
-                    enabled: bool,
-                },
-                script: {
-                    asynch: bool,
-                },
-                serviceworker: {
-                    enabled: bool,
-                    timeout_seconds: i64,
-                },
-                servo_helpers: {
-                    enabled: bool,
-                },
-                servoparser: {
-                    async_html_tokenizer: {
-                        enabled: bool,
-                    }
-                },
-                shadowdom: {
-                    enabled: bool,
-                },
-                svg: {
-                    enabled: bool,
-                },
-                testable_crash: {
-                    enabled: bool,
-                },
-                testbinding: {
-                    enabled: bool,
-                    prefcontrolled: {
-                        #[serde(default)]
-                        enabled: bool,
-                    },
-                    prefcontrolled2: {
-                        #[serde(default)]
-                        enabled: bool,
-                    },
-                    preference_value: {
-                        #[serde(default)]
-                        falsy: bool,
-                        #[serde(default)]
-                        quote_string_test: String,
-                        #[serde(default)]
-                        space_string_test: String,
-                        #[serde(default)]
-                        string_empty: String,
-                        #[serde(default)]
-                        string_test: String,
-                        #[serde(default)]
-                        truthy: bool,
-                    },
-                },
-                testing: {
-                    element: {
-                        activation: {
-                            #[serde(default)]
-                            enabled: bool,
-                        }
-                    },
-                    html_input_element: {
-                        select_files: {
-                            #[serde(rename = "dom.testing.htmlinputelement.select_files.enabled")]
-                            enabled: bool,
-                        }
-                    },
-                },
-                testperf: {
-                    #[serde(default)]
-                    enabled: bool,
-                },
-                webgl2: {
-                    /// Enable WebGL2 APIs.
-                    enabled: bool,
-                },
-                webrtc: {
-                    transceiver: {
-                        enabled: bool,
-                    },
-                    #[serde(default)]
-                    enabled: bool,
-                },
-                webvtt: {
-                    enabled: bool,
-                },
-                webxr: {
-                    #[serde(default)]
-                    enabled: bool,
-                    #[serde(default)]
-                    test: bool,
-                    first_person_observer_view: bool,
-                    glwindow: {
-                        /// Enable servo/webxr's glwindow port. This is enabled only if openxr is
-                        /// disabled.
-                        #[serde(default)]
-                        enabled: bool,
-                        #[serde(rename = "dom.webxr.glwindow.left-right")]
-                        left_right: bool,
-                        #[serde(rename = "dom.webxr.glwindow.red-cyan")]
-                        red_cyan: bool,
-                        spherical: bool,
-                        cubemap: bool,
-                    },
-                    hands: {
-                        #[serde(default)]
-                        enabled: bool,
-                    },
-                    layers: {
-                        enabled: bool,
-                    },
-                    openxr: {
-                        /// Enable servo/webxr's openxr port
-                        enabled: bool,
-                    },
-                    sessionavailable: bool,
-                    #[serde(rename = "dom.webxr.unsafe-assume-user-intent")]
-                    unsafe_assume_user_intent: bool,
-                },
-                worklet: {
-                    blockingsleep: {
-                        #[serde(default)]
-                        enabled: bool,
-                    },
-                    #[serde(default)]
-                    enabled: bool,
-                    testing: {
-                        #[serde(default)]
-                        enabled: bool,
-                    },
-                    timeout_ms: i64,
-                },
-                xpath: {
-                    enabled: bool,
-                }
-            },
-            gfx: {
-                subpixel_text_antialiasing: {
-                    #[serde(rename = "gfx.subpixel-text-antialiasing.enabled")]
-                    enabled: bool,
-                },
-                texture_swizzling: {
-                    #[serde(rename = "gfx.texture-swizzling.enabled")]
-                    enabled: bool,
-                },
-            },
-            js: {
-                asmjs: {
-                    enabled: bool,
-                },
-                asyncstack: {
-                    enabled: bool,
-                },
-                baseline_interpreter: {
-                    enabled: bool,
-                },
-                /// Whether to disable the jit within SpiderMonkey
-                disable_jit: bool,
-                baseline_jit: {
-                    enabled: bool,
-                    unsafe_eager_compilation: {
-                        enabled: bool,
-                    },
-                },
-                discard_system_source: {
-                    enabled: bool,
-                },
-                dump_stack_on_debuggee_would_run: {
-                    enabled: bool,
-                },
-                ion: {
-                    enabled: bool,
-                    offthread_compilation: {
-                        enabled: bool,
-                    },
-                    unsafe_eager_compilation: {
-                        enabled: bool,
-                    },
-                },
-                mem: {
-                    gc: {
-                        allocation_threshold_mb: i64,
-                        allocation_threshold_factor: i64,
-                        allocation_threshold_avoid_interrupt_factor: i64,
-                        compacting: {
-                            enabled: bool,
-                        },
-                        decommit_threshold_mb: i64,
-                        dynamic_heap_growth: {
-                            enabled: bool,
-                        },
-                        dynamic_mark_slice: {
-                            enabled: bool,
-                        },
-                        empty_chunk_count_max: i64,
-                        empty_chunk_count_min: i64,
-                        high_frequency_heap_growth_max: i64,
-                        high_frequency_heap_growth_min: i64,
-                        high_frequency_high_limit_mb: i64,
-                        high_frequency_low_limit_mb: i64,
-                        high_frequency_time_limit_ms: i64,
-                        incremental: {
-                            enabled: bool,
-                            slice_ms: i64,
-                        },
-                        low_frequency_heap_growth: i64,
-                        per_zone: {
-                            enabled: bool,
-                        },
-                        zeal: {
-                            frequency: i64,
-                            level: i64,
-                        },
-                    },
-                    max: i64,
-                },
-                native_regex: {
-                    enabled: bool,
-                },
-                offthread_compilation: {
-                    enabled: bool,
-                },
-                parallel_parsing: {
-                    enabled: bool,
-                },
-                shared_memory: {
-                    enabled: bool,
-                },
-                throw_on_asmjs_validation_failure: {
-                    enabled: bool,
-                },
-                throw_on_debuggee_would_run: {
-                    enabled: bool,
-                },
-                timers: {
-                    minimum_duration: i64,
-                },
-                wasm: {
-                    baseline: {
-                        enabled: bool,
-                    },
-                    enabled: bool,
-                    ion: {
-                        enabled: bool,
-                    }
-                },
-                werror: {
-                    enabled: bool,
-                },
-            },
-            layout: {
-                animations: {
-                    test: {
-                        enabled: bool,
-                    }
-                },
-                columns: {
-                    enabled: bool,
-                },
-                css: {
-                    transition_behavior: {
-                        #[serde(rename = "layout.css.transition-behavior.enabled")]
-                        enabled: bool,
-                    }
-                },
-                flexbox: {
-                    enabled: bool,
-                },
-                grid: {
-                    enabled: bool,
-                },
-                legacy_layout: bool,
-                #[serde(default = "default_layout_threads")]
-                threads: i64,
-                writing_mode: {
-                    #[serde(rename = "layout.writing-mode.enabled")]
-                    enabled: bool,
-                }
-            },
-            media: {
-                glvideo: {
-                    /// Enable hardware acceleration for video playback.
-                    enabled: bool,
-                },
-                testing: {
-                    /// Enable a non-standard event handler for verifying behavior of media elements during tests.
-                    enabled: bool,
-                }
-            },
-            network: {
-                enforce_tls: {
-                    enabled: bool,
-                    localhost: bool,
-                    onion: bool,
-                },
-                http_cache: {
-                    #[serde(rename = "network.http-cache.disabled")]
-                    disabled: bool,
-                },
-                local_directory_listing: {
-                    enabled: bool,
-                },
-                mime: {
-                    sniff: bool,
-                },
-                tls: {
-                    /// Ignore `std::io::Error` with `ErrorKind::UnexpectedEof` received when a TLS connection
-                    /// is closed without a close_notify.
-                    ///
-                    /// Used for tests because WPT server doesn't properly close the TLS connection.
-                    // TODO: remove this when WPT server is updated to use a proper TLS implementation.
-                    ignore_unexpected_eof: bool,
-                },
-            },
-            session_history: {
-                #[serde(rename = "session-history.max-length")]
-                max_length: i64,
-            },
-            shell: {
-                background_color: {
-                    /// The background color of shell's viewport. This will be used by OpenGL's `glClearColor`.
-                    #[serde(rename = "shell.background-color.rgba")]
-                    rgba: [f64; 4],
-                },
-                crash_reporter: {
-                    enabled: bool,
-                },
-                /// URL string of the homepage.
-                homepage: String,
-                #[serde(rename = "shell.native-orientation")]
-                native_orientation: String,
-                native_titlebar: {
-                    /// Enable native window's titlebar and decorations.
-                    #[serde(rename = "shell.native-titlebar.enabled")]
-                    enabled: bool,
-                },
-                /// URL string of the search engine page (for example <https://google.com> or and <https://duckduckgo.com>.
-                searchpage: String,
-            },
-            webgl: {
-                testing: {
-                    context_creation_error: bool,
-                }
-            },
-        }
+impl Default for Preferences {
+    fn default() -> Self {
+        Self::new()
     }
 }
diff --git a/components/config/tests/prefs.rs b/components/config/tests/prefs.rs
deleted file mode 100644
index 4ff37299a8d..00000000000
--- a/components/config/tests/prefs.rs
+++ /dev/null
@@ -1,333 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
-
-use std::collections::HashMap;
-use std::error::Error;
-use std::fs::{self, File};
-use std::io::{Read, Write};
-
-use servo_config::basedir;
-use servo_config::pref_util::Preferences;
-use servo_config::prefs::{read_prefs_map, PrefValue};
-
-#[test]
-fn test_create_prefs_map() {
-    let json_str = "{
-        \"layout.writing-mode.enabled\": true,
-        \"network.mime.sniff\": false,
-        \"shell.homepage\": \"https://servo.org\"
-    }";
-    let prefs = read_prefs_map(json_str);
-    assert!(prefs.is_ok());
-    let prefs = prefs.unwrap();
-    assert_eq!(prefs.len(), 3);
-}
-
-#[test]
-fn test_generated_accessors_get() {
-    let prefs: gen::TestPrefs = serde_json::from_str(DEF_JSON_STR).unwrap();
-    let map: HashMap<String, PrefValue> = gen::TEST_PREF_ACCESSORS
-        .iter()
-        .map(move |(key, accessor)| {
-            let pref_value = (accessor.getter)(&prefs);
-            (key.clone(), pref_value)
-        })
-        .collect();
-
-    assert_eq!(&PrefValue::from("hello"), map.get("pref_string").unwrap());
-    assert_eq!(&PrefValue::from(23_i64), map.get("pref_i64").unwrap());
-    assert_eq!(&PrefValue::from(1.5_f64), map.get("pref_f64").unwrap());
-    assert_eq!(&PrefValue::from(true), map.get("pref_bool").unwrap());
-    assert_eq!(
-        &PrefValue::from(333_i64),
-        map.get("group.nested.nested_i64").unwrap()
-    );
-    assert_eq!(&PrefValue::from(42_i64), map.get("a.renamed.pref").unwrap());
-}
-
-#[test]
-fn test_generated_accessors_set() {
-    let mut prefs: gen::TestPrefs = serde_json::from_str(DEF_JSON_STR).unwrap();
-    let setters: HashMap<String, _> = gen::TEST_PREF_ACCESSORS
-        .iter()
-        .map(|(key, accessor)| (key.clone(), &accessor.setter))
-        .collect();
-
-    (setters.get("pref_string").unwrap())(&mut prefs, PrefValue::Str(String::from("boo")));
-    (setters.get("pref_i64").unwrap())(&mut prefs, PrefValue::Int(-25));
-    (setters.get("pref_f64").unwrap())(&mut prefs, PrefValue::Float(-1.9));
-    (setters.get("pref_bool").unwrap())(&mut prefs, PrefValue::Bool(false));
-    (setters.get("group.nested.nested_i64").unwrap())(&mut prefs, PrefValue::Int(10));
-    (setters.get("a.renamed.pref").unwrap())(&mut prefs, PrefValue::Int(11));
-
-    assert_eq!("boo", prefs.pref_string);
-    assert_eq!(-25, prefs.pref_i64);
-    assert_eq!(-1.9, prefs.pref_f64);
-    assert_eq!(false, prefs.pref_bool);
-    assert_eq!(10, prefs.group.nested.nested_i64);
-    assert_eq!(11, prefs.group.nested.renamed);
-}
-
-#[test]
-fn test_static_struct() {
-    let prefs: gen::TestPrefs = serde_json::from_str(DEF_JSON_STR).unwrap();
-    assert_eq!("hello", prefs.pref_string);
-    assert_eq!(23, prefs.pref_i64);
-    assert_eq!(1.5, prefs.pref_f64);
-    assert_eq!(true, prefs.pref_bool);
-    assert_eq!(333, prefs.group.nested.nested_i64);
-    assert_eq!(42, prefs.group.nested.renamed);
-}
-
-#[test]
-fn test_set_pref() {
-    let prefs = Preferences::new(gen::TestPrefs::default(), &gen::TEST_PREF_ACCESSORS);
-    assert_eq!(Some(0), prefs.get("group.nested.nested_i64").as_i64());
-    let result = prefs.set("group.nested.nested_i64", 1);
-    assert_eq!(true, result.is_ok());
-    assert_eq!(Some(1), prefs.get("group.nested.nested_i64").as_i64());
-    assert_eq!(1, prefs.values().read().unwrap().group.nested.nested_i64);
-}
-
-#[test]
-fn test_set_unknown_pref_is_err() -> Result<(), Box<dyn Error>> {
-    let prefs = Preferences::new(gen::TestPrefs::default(), &gen::TEST_PREF_ACCESSORS);
-    let result = prefs.set("unknown_pref", 1);
-    assert_eq!(true, result.is_err());
-    Ok(())
-}
-
-#[test]
-fn test_reset_pref() -> Result<(), Box<dyn Error>> {
-    let mut def_prefs = gen::TestPrefs::default();
-    def_prefs.group.nested.nested_i64 = 999;
-    let prefs = Preferences::new(def_prefs, &gen::TEST_PREF_ACCESSORS);
-    assert_eq!(Some(999), prefs.get("group.nested.nested_i64").as_i64());
-
-    prefs.set("group.nested.nested_i64", 1)?;
-    assert_eq!(Some(1), prefs.get("group.nested.nested_i64").as_i64());
-
-    prefs.reset("group.nested.nested_i64")?;
-    assert_eq!(Some(999), prefs.get("group.nested.nested_i64").as_i64());
-    assert_eq!(999, prefs.values().read().unwrap().group.nested.nested_i64);
-    Ok(())
-}
-
-#[test]
-fn test_default_values() -> Result<(), Box<dyn Error>> {
-    let def_prefs: gen::TestPrefs = serde_json::from_str(DEF_JSON_STR)?;
-    let prefs = Preferences::new(def_prefs, &gen::TEST_PREF_ACCESSORS);
-    assert_eq!(Some(0), prefs.get("default_value").as_i64());
-    assert_eq!(Some(555), prefs.get("computed_default_value").as_i64());
-    Ok(())
-}
-
-#[test]
-fn test_override_default_values() -> Result<(), Box<dyn Error>> {
-    let def_prefs: gen::TestPrefs = serde_json::from_str(WITHOUT_DEFAULTS_JSON_STR)?;
-    let prefs = Preferences::new(def_prefs, &gen::TEST_PREF_ACCESSORS);
-    assert_eq!(Some(-1), prefs.get("default_value").as_i64());
-    assert_eq!(Some(-1), prefs.get("computed_default_value").as_i64());
-    Ok(())
-}
-
-#[test]
-fn test_update_reset_default_values() -> Result<(), Box<dyn Error>> {
-    let def_prefs: gen::TestPrefs = serde_json::from_str(DEF_JSON_STR)?;
-    let prefs = Preferences::new(def_prefs, &gen::TEST_PREF_ACCESSORS);
-
-    prefs.set("default_value", 99)?;
-    prefs.set("computed_default_value", 199)?;
-    assert_eq!(Some(99), prefs.get("default_value").as_i64());
-    assert_eq!(Some(199), prefs.get("computed_default_value").as_i64());
-
-    prefs.reset("default_value")?;
-    prefs.reset("computed_default_value")?;
-    assert_eq!(Some(0), prefs.get("default_value").as_i64());
-    assert_eq!(Some(555), prefs.get("computed_default_value").as_i64());
-    Ok(())
-}
-
-#[test]
-fn test_update_reset_overridden_default_values() -> Result<(), Box<dyn Error>> {
-    let def_prefs: gen::TestPrefs = serde_json::from_str(WITHOUT_DEFAULTS_JSON_STR)?;
-    let prefs = Preferences::new(def_prefs, &gen::TEST_PREF_ACCESSORS);
-    prefs.set("default_value", 99)?;
-    prefs.set("computed_default_value", 199)?;
-    assert_eq!(Some(99), prefs.get("default_value").as_i64());
-    assert_eq!(Some(199), prefs.get("computed_default_value").as_i64());
-
-    prefs.reset("default_value")?;
-    prefs.reset("computed_default_value")?;
-    assert_eq!(Some(-1), prefs.get("default_value").as_i64());
-    assert_eq!(Some(-1), prefs.get("computed_default_value").as_i64());
-    Ok(())
-}
-
-#[test]
-fn test_user_prefs_override_and_reset() -> Result<(), Box<dyn Error>> {
-    let mut def_prefs = gen::TestPrefs::default();
-    def_prefs.group.nested.nested_i64 = 999;
-    let prefs = Preferences::new(def_prefs, &gen::TEST_PREF_ACCESSORS);
-
-    prefs.set("group.nested.nested_i64", 45)?;
-    assert_eq!(Some(45), prefs.get("group.nested.nested_i64").as_i64());
-
-    prefs.reset("group.nested.nested_i64")?;
-    assert_eq!(Some(999), prefs.get("group.nested.nested_i64").as_i64());
-    Ok(())
-}
-
-#[test]
-fn test_reset_all() -> Result<(), Box<dyn Error>> {
-    let def_prefs: gen::TestPrefs = serde_json::from_str(DEF_JSON_STR)?;
-    let prefs = Preferences::new(def_prefs, &gen::TEST_PREF_ACCESSORS);
-    prefs.set_all(read_prefs_map(USER_JSON_STR)?)?;
-
-    let values = prefs.values();
-    assert_eq!("bye", values.read().unwrap().pref_string);
-    assert_eq!(-1, values.read().unwrap().pref_i64);
-    assert_eq!(-1.0, values.read().unwrap().pref_f64);
-    assert_eq!(false, values.read().unwrap().pref_bool);
-    assert_eq!(-1, values.read().unwrap().group.nested.nested_i64);
-    assert_eq!(-1, values.read().unwrap().group.nested.renamed);
-
-    prefs.reset_all();
-
-    let values = prefs.values();
-    assert_eq!("hello", values.read().unwrap().pref_string);
-    assert_eq!(23, values.read().unwrap().pref_i64);
-    assert_eq!(1.5, values.read().unwrap().pref_f64);
-    assert_eq!(true, values.read().unwrap().pref_bool);
-    assert_eq!(333, values.read().unwrap().group.nested.nested_i64);
-    assert_eq!(42, values.read().unwrap().group.nested.renamed);
-    Ok(())
-}
-
-#[test]
-fn test_set_all_from_map() -> Result<(), Box<dyn Error>> {
-    let def_prefs: gen::TestPrefs = serde_json::from_str(DEF_JSON_STR)?;
-    let prefs = Preferences::new(def_prefs, &gen::TEST_PREF_ACCESSORS);
-    prefs.set_all(read_prefs_map(USER_JSON_STR)?)?;
-
-    let mut overrides = HashMap::new();
-    overrides.insert(String::from("pref_string"), PrefValue::from("new value"));
-    overrides.insert(
-        String::from("group.nested.nested_i64"),
-        PrefValue::from(1001),
-    );
-    overrides.insert(String::from("a.renamed.pref"), PrefValue::from(47));
-
-    let result = prefs.set_all(overrides.into_iter());
-    assert_eq!(true, result.is_ok());
-
-    let values = prefs.values();
-    assert_eq!("new value", values.read().unwrap().pref_string);
-    assert_eq!(1001, values.read().unwrap().group.nested.nested_i64);
-    assert_eq!(47, values.read().unwrap().group.nested.renamed);
-    Ok(())
-}
-
-#[test]
-fn test_set_all_error_on_unknown_field() -> Result<(), Box<dyn Error>> {
-    let def_prefs: gen::TestPrefs = serde_json::from_str(DEF_JSON_STR)?;
-    let prefs = Preferences::new(def_prefs, &gen::TEST_PREF_ACCESSORS);
-
-    let mut overrides = HashMap::new();
-    overrides.insert(String::from("doesnt_exist"), PrefValue::from(1001));
-
-    let result = prefs.set_all(overrides.into_iter());
-    assert_eq!(true, result.is_err());
-    Ok(())
-}
-
-#[cfg(not(target_os = "android"))]
-#[test]
-fn test_default_config_dir_create_read_write() {
-    let json_str = "{\
-                    \"layout.writing-mode.enabled\": true,\
-                    \"extra.stuff\": false,\
-                    \"shell.homepage\": \"https://google.com\"\
-                    }";
-    let mut expected_json = String::new();
-    let config_path = basedir::default_config_dir().unwrap();
-
-    if !config_path.exists() {
-        fs::create_dir_all(&config_path).unwrap();
-    }
-
-    let json_path = config_path.join("test_config.json");
-
-    let mut fd = File::create(&json_path).unwrap();
-    assert_eq!(json_path.exists(), true);
-
-    fd.write_all(json_str.as_bytes()).unwrap();
-    let mut fd = File::open(&json_path).unwrap();
-    fd.read_to_string(&mut expected_json).unwrap();
-
-    assert_eq!(json_str, expected_json);
-
-    fs::remove_file(&json_path).unwrap();
-}
-
-static DEF_JSON_STR: &'static str = r#"{
-    "pref_string": "hello",
-    "pref_i64": 23,
-    "pref_f64": 1.5,
-    "pref_bool": true,
-    "group.nested.nested_i64": 333,
-    "a.renamed.pref": 42
-}"#;
-
-static USER_JSON_STR: &'static str = r#"{
-    "pref_string": "bye",
-    "pref_i64": -1,
-    "pref_f64": -1.0,
-    "pref_bool": false,
-    "group.nested.nested_i64": -1,
-    "a.renamed.pref": -1
-}"#;
-
-static WITHOUT_DEFAULTS_JSON_STR: &'static str = r#"{
-    "pref_string": "bye",
-    "pref_i64": -1,
-    "pref_f64": -1.0,
-    "pref_bool": false,
-    "group.nested.nested_i64": -1,
-    "a.renamed.pref": -1,
-    "computed_default_value": -1,
-    "default_value": -1
-}"#;
-
-mod gen {
-    use serde::{Deserialize, Serialize};
-    use servo_config::pref_util::{Accessor, PrefValue};
-    use servo_config_plugins::build_structs;
-
-    fn compute_default() -> i64 {
-        555
-    }
-
-    build_structs! {
-        accessor_type = Accessor::<TestPrefs, PrefValue>,
-        gen_accessors = TEST_PREF_ACCESSORS,
-        gen_types = TestPrefs {
-            pref_string: String,
-            pref_i64: i64,
-            pref_f64: f64,
-            pref_bool: bool,
-            #[serde(default)]
-            default_value: i64,
-            #[serde(default = "compute_default")]
-            computed_default_value: i64,
-            group: {
-                nested: {
-                    nested_i64: i64,
-                    #[serde(rename = "a.renamed.pref")]
-                    renamed: i64,
-                }
-            }
-        }
-    }
-}
diff --git a/components/config_plugins/lib.rs b/components/config_plugins/lib.rs
deleted file mode 100644
index 4d2eb61943c..00000000000
--- a/components/config_plugins/lib.rs
+++ /dev/null
@@ -1,206 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
-
-use std::collections::{hash_map, HashMap};
-use std::fmt::Write;
-use std::iter;
-
-use itertools::Itertools;
-use proc_macro2::{Span, TokenStream};
-use quote::*;
-use syn::parse::Result;
-use syn::spanned::Spanned;
-use syn::{parse_macro_input, Attribute, Ident, LitStr, Path};
-
-mod parse;
-use parse::*;
-
-#[proc_macro]
-pub fn build_structs(tokens: proc_macro::TokenStream) -> proc_macro::TokenStream {
-    let input: MacroInput = parse_macro_input!(tokens);
-    let out = Build::new(&input)
-        .build(&input.type_def)
-        .unwrap_or_else(|e| syn::Error::new(e.span(), e).to_compile_error());
-    out.into()
-}
-
-struct Build {
-    root_type_name: Ident,
-    gen_accessors: Ident,
-    accessor_type: Path,
-    output: TokenStream,
-    path_stack: Vec<Ident>,
-    path_map: HashMap<String, Vec<Ident>>,
-}
-
-impl Build {
-    fn new(input: &MacroInput) -> Self {
-        Build {
-            root_type_name: input.type_def.type_name.clone(),
-            gen_accessors: input.gen_accessors.clone(),
-            accessor_type: input.accessor_type.clone(),
-            output: TokenStream::new(),
-            path_stack: Vec::new(),
-            path_map: HashMap::new(),
-        }
-    }
-
-    fn build(mut self, type_def: &RootTypeDef) -> Result<TokenStream> {
-        self.walk(&type_def.type_def)?;
-        self.build_accessors();
-        Ok(self.output)
-    }
-
-    fn walk(&mut self, type_def: &NewTypeDef) -> Result<()> {
-        self.define_pref_struct(type_def)?;
-
-        for field in type_def.fields.iter() {
-            self.path_stack.push(field.name.clone());
-
-            if let FieldType::NewTypeDef(new_def) = &field.field_type {
-                self.walk(new_def)?;
-            } else {
-                let pref_name =
-                    self.pref_name(field, &self.path_stack[..self.path_stack.len() - 1]);
-                if let hash_map::Entry::Vacant(slot) = self.path_map.entry(pref_name) {
-                    slot.insert(self.path_stack.clone());
-                } else {
-                    return Err(err(&field.name, "duplicate preference name"));
-                }
-            }
-
-            self.path_stack.pop();
-        }
-        Ok(())
-    }
-
-    fn define_pref_struct(&mut self, type_def: &NewTypeDef) -> Result<()> {
-        let struct_name = self.path_to_name(self.path_stack.iter());
-        let field_defs = type_def
-            .fields
-            .iter()
-            .map(|field| self.field_to_tokens(field, &self.path_stack))
-            .collect::<Result<Vec<_>>>()?;
-        self.output.extend(quote! {
-            #[derive(Clone, Debug, Default, Deserialize, PartialEq, Serialize)]
-            #[allow(non_camel_case_types)]
-            pub struct #struct_name {
-                #(#field_defs), *
-            }
-        });
-        Ok(())
-    }
-
-    fn build_accessors(&mut self) {
-        let accessor_type = &self.accessor_type;
-        let values = self.path_map.iter().map(|(key, path)| {
-            quote! {
-                map.insert(String::from(#key),
-                    #accessor_type::new(
-                        |prefs| prefs #(.#path)*.clone().into(),
-                        |prefs, value| prefs #(.#path)* = value.into()
-                    )
-                 );
-            }
-        });
-
-        let gen_accessors = &self.gen_accessors;
-        let num_prefs = self.path_map.len();
-
-        self.output.extend(quote! {
-            pub static #gen_accessors: std::sync::LazyLock<std::collections::HashMap<String, #accessor_type>> =
-                std::sync::LazyLock::new(|| {
-                    let mut map = std::collections::HashMap::with_capacity(#num_prefs);
-                    #(#values)*
-                    map
-                });
-        });
-    }
-
-    fn pref_name(&self, field: &Field, path_stack: &[Ident]) -> String {
-        field
-            .get_field_name_mapping()
-            .map(|pref_attr| pref_attr.value())
-            .unwrap_or_else(|| {
-                Itertools::intersperse(
-                    path_stack
-                        .iter()
-                        .chain(iter::once(&field.name))
-                        .map(Ident::to_string),
-                    String::from("."),
-                )
-                .collect()
-            })
-    }
-
-    fn field_to_tokens(&self, field: &Field, path_stack: &[Ident]) -> Result<TokenStream> {
-        let name = &field.name;
-        Ok(match &field.field_type {
-            FieldType::NewTypeDef(_) => {
-                let type_name = self.path_to_name(path_stack.iter().chain(iter::once(name)));
-                quote! {
-                    #[serde(flatten)]
-                    pub #name: #type_name
-                }
-            },
-            FieldType::Existing(type_name) => {
-                let pref_name = self.pref_name(field, path_stack);
-                let attributes = field.get_attributes(&pref_name);
-                quote! {
-                    #attributes
-                    pub #name: #type_name
-                }
-            },
-        })
-    }
-
-    fn path_to_name<'p, P: Iterator<Item = &'p Ident> + 'p>(&self, path: P) -> Ident {
-        let mut name = format!("{}", self.root_type_name);
-        for part in path {
-            name.write_fmt(format_args!("__{}", part)).unwrap();
-        }
-        Ident::new(&name, Span::call_site())
-    }
-}
-
-impl Field {
-    fn get_attributes(&self, pref_name: &str) -> TokenStream {
-        let mut tokens = TokenStream::new();
-        for attr in self
-            .attributes
-            .iter()
-            .filter(|attr| attr_to_pref_name(attr).is_none())
-        {
-            attr.to_tokens(&mut tokens);
-        }
-        tokens.extend(quote! {
-            #[serde(rename = #pref_name)]
-        });
-        tokens
-    }
-
-    fn get_field_name_mapping(&self) -> Option<LitStr> {
-        self.attributes.iter().filter_map(attr_to_pref_name).next()
-    }
-}
-
-fn attr_to_pref_name(attr: &Attribute) -> Option<LitStr> {
-    if attr.path().is_ident("serde") {
-        // If `parse_nested_meta()` fails, `result` will remain None.
-        let mut result = None;
-        let _ = attr.parse_nested_meta(|meta| {
-            if meta.path.is_ident("rename") {
-                result = Some(meta.value()?.parse()?);
-            }
-            Ok(())
-        });
-        result
-    } else {
-        None
-    }
-}
-
-fn err<S: Spanned>(s: S, msg: &str) -> syn::Error {
-    syn::Error::new(s.span(), msg)
-}
diff --git a/components/config_plugins/parse.rs b/components/config_plugins/parse.rs
deleted file mode 100644
index 63a3d66dfda..00000000000
--- a/components/config_plugins/parse.rs
+++ /dev/null
@@ -1,151 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
-
-use proc_macro2::Span;
-use syn::parse::{Parse, ParseStream, Result};
-use syn::punctuated::Punctuated;
-use syn::{braced, token, Attribute, Ident, Path, Token, Type};
-
-#[allow(non_camel_case_types)]
-mod kw {
-    syn::custom_keyword!(accessor_type);
-    syn::custom_keyword!(gen_accessors);
-    syn::custom_keyword!(gen_types);
-}
-
-pub struct MacroInput {
-    pub type_def: RootTypeDef,
-    pub gen_accessors: Ident,
-    pub accessor_type: Path,
-}
-
-enum MacroArg {
-    GenAccessors(ArgInner<kw::gen_accessors, Ident>),
-    AccessorType(ArgInner<kw::accessor_type, Path>),
-    Types(ArgInner<kw::gen_types, RootTypeDef>),
-}
-
-struct ArgInner<K, V> {
-    _field_kw: K,
-    _equals: Token![=],
-    value: V,
-}
-
-pub struct Field {
-    pub attributes: Vec<Attribute>,
-    pub name: Ident,
-    _colon: Token![:],
-    pub field_type: FieldType,
-}
-
-pub enum FieldType {
-    Existing(Type),
-    NewTypeDef(NewTypeDef),
-}
-
-pub struct NewTypeDef {
-    _braces: token::Brace,
-    pub fields: Punctuated<Field, Token![, ]>,
-}
-
-pub struct RootTypeDef {
-    pub type_name: Ident,
-    pub type_def: NewTypeDef,
-}
-
-impl Parse for MacroInput {
-    fn parse(input: ParseStream<'_>) -> Result<Self> {
-        let fields: Punctuated<MacroArg, Token![, ]> =
-            Punctuated::parse_terminated_with(input, MacroArg::parse)?;
-        let mut gen_accessors = None;
-        let mut type_def = None;
-        let mut accessor_type = None;
-        for arg in fields.into_iter() {
-            match arg {
-                MacroArg::GenAccessors(ArgInner { value, .. }) => gen_accessors = Some(value),
-                MacroArg::AccessorType(ArgInner { value, .. }) => accessor_type = Some(value),
-                MacroArg::Types(ArgInner { value, .. }) => type_def = Some(value),
-            }
-        }
-
-        fn missing_attr(att_name: &str) -> syn::Error {
-            syn::Error::new(
-                Span::call_site(),
-                format!("Expected `{}` attribute", att_name),
-            )
-        }
-
-        Ok(MacroInput {
-            type_def: type_def.ok_or_else(|| missing_attr("gen_types"))?,
-            gen_accessors: gen_accessors.ok_or_else(|| missing_attr("gen_accessors"))?,
-            accessor_type: accessor_type.ok_or_else(|| missing_attr("accessor_type"))?,
-        })
-    }
-}
-
-impl Parse for MacroArg {
-    fn parse(input: ParseStream<'_>) -> Result<Self> {
-        let lookahead = input.lookahead1();
-        if lookahead.peek(kw::gen_types) {
-            Ok(MacroArg::Types(input.parse()?))
-        } else if lookahead.peek(kw::gen_accessors) {
-            Ok(MacroArg::GenAccessors(input.parse()?))
-        } else if lookahead.peek(kw::accessor_type) {
-            Ok(MacroArg::AccessorType(input.parse()?))
-        } else {
-            Err(lookahead.error())
-        }
-    }
-}
-
-impl<K: Parse, V: Parse> Parse for ArgInner<K, V> {
-    fn parse(input: ParseStream<'_>) -> Result<Self> {
-        Ok(ArgInner {
-            _field_kw: input.parse()?,
-            _equals: input.parse()?,
-            value: input.parse()?,
-        })
-    }
-}
-
-impl Parse for Field {
-    fn parse(input: ParseStream<'_>) -> Result<Self> {
-        Ok(Field {
-            attributes: input.call(Attribute::parse_outer)?,
-            name: input.parse()?,
-            _colon: input.parse()?,
-            field_type: input.parse()?,
-        })
-    }
-}
-
-impl Parse for RootTypeDef {
-    fn parse(input: ParseStream<'_>) -> Result<Self> {
-        Ok(RootTypeDef {
-            type_name: input.parse()?,
-            type_def: input.parse()?,
-        })
-    }
-}
-
-impl Parse for NewTypeDef {
-    fn parse(input: ParseStream<'_>) -> Result<Self> {
-        let content;
-        #[allow(clippy::mixed_read_write_in_expression)]
-        Ok(NewTypeDef {
-            _braces: braced!(content in input),
-            fields: Punctuated::parse_terminated_with(&content, Field::parse)?,
-        })
-    }
-}
-
-impl Parse for FieldType {
-    fn parse(input: ParseStream<'_>) -> Result<Self> {
-        if input.peek(token::Brace) {
-            Ok(FieldType::NewTypeDef(input.parse()?))
-        } else {
-            Ok(FieldType::Existing(input.parse()?))
-        }
-    }
-}
diff --git a/components/constellation/constellation.rs b/components/constellation/constellation.rs
index 55777f1b6a1..0558c234f51 100644
--- a/components/constellation/constellation.rs
+++ b/components/constellation/constellation.rs
@@ -660,7 +660,7 @@ where
                 // a dedicated per-process hang monitor will be initialized later inside the content process.
                 // See run_content_process in servo/lib.rs
                 let (background_monitor_register, background_hang_monitor_control_ipc_senders) =
-                    if opts::multiprocess() {
+                    if opts::get().multiprocess {
                         (None, vec![])
                     } else {
                         let (
@@ -2502,7 +2502,7 @@ where
                 };
                 let content = ServiceWorkerUnprivilegedContent::new(sw_senders, origin);
 
-                if opts::multiprocess() {
+                if opts::get().multiprocess {
                     if content.spawn_multiprocess().is_err() {
                         return warn!("Failed to spawn process for SW manager.");
                     }
@@ -5034,7 +5034,7 @@ where
         let pipelines_to_evict = {
             let session_history = self.get_joint_session_history(top_level_browsing_context_id);
 
-            let history_length = pref!(session_history.max_length) as usize;
+            let history_length = pref!(session_history_max_length) as usize;
 
             // The past is stored with older entries at the front.
             // We reverse the iter so that newer entries are at the front and then
diff --git a/components/constellation/pipeline.rs b/components/constellation/pipeline.rs
index d8dd2028ebb..73bdd612884 100644
--- a/components/constellation/pipeline.rs
+++ b/components/constellation/pipeline.rs
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use std::borrow::Cow;
-use std::collections::{HashMap, HashSet};
+use std::collections::HashSet;
 use std::rc::Rc;
 use std::sync::Arc;
 
@@ -39,8 +39,7 @@ use script_traits::{
 };
 use serde::{Deserialize, Serialize};
 use servo_config::opts::{self, Opts};
-use servo_config::prefs;
-use servo_config::prefs::PrefValue;
+use servo_config::prefs::{self, Preferences};
 use servo_url::ServoUrl;
 use webrender_api::DocumentId;
 use webrender_traits::CrossProcessCompositorApi;
@@ -283,7 +282,7 @@ impl Pipeline {
                     load_data: state.load_data.clone(),
                     script_port,
                     opts: (*opts::get()).clone(),
-                    prefs: prefs::pref_map().iter().collect(),
+                    prefs: Box::new(prefs::get().clone()),
                     pipeline_namespace_id: state.pipeline_namespace_id,
                     webrender_document: state.webrender_document,
                     cross_process_compositor_api: state
@@ -300,7 +299,7 @@ impl Pipeline {
                 // Spawn the child process.
                 //
                 // Yes, that's all there is to it!
-                let bhm_control_chan = if opts::multiprocess() {
+                let bhm_control_chan = if opts::get().multiprocess {
                     let (bhm_control_chan, bhm_control_port) =
                         ipc::channel().expect("Sampler chan");
                     unprivileged_pipeline_content.bhm_control_port = Some(bhm_control_port);
@@ -490,7 +489,7 @@ pub struct UnprivilegedPipelineContent {
     load_data: LoadData,
     script_port: IpcReceiver<ConstellationControlMsg>,
     opts: Opts,
-    prefs: HashMap<String, PrefValue>,
+    prefs: Box<Preferences>,
     pipeline_namespace_id: PipelineNamespaceId,
     cross_process_compositor_api: CrossProcessCompositorApi,
     webrender_document: DocumentId,
@@ -581,7 +580,7 @@ impl UnprivilegedPipelineContent {
         self.opts.clone()
     }
 
-    pub fn prefs(&self) -> HashMap<String, PrefValue> {
-        self.prefs.clone()
+    pub fn prefs(&self) -> &Preferences {
+        &self.prefs
     }
 }
diff --git a/components/constellation/sandboxing.rs b/components/constellation/sandboxing.rs
index ffb0d44d5cc..0f883b4743a 100644
--- a/components/constellation/sandboxing.rs
+++ b/components/constellation/sandboxing.rs
@@ -2,7 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use std::collections::HashMap;
 #[cfg(not(windows))]
 use std::env;
 use std::ffi::OsStr;
@@ -23,7 +22,7 @@ use gaol::profile::{Operation, PathPattern, Profile};
 use ipc_channel::Error;
 use serde::{Deserialize, Serialize};
 use servo_config::opts::Opts;
-use servo_config::prefs::PrefValue;
+use servo_config::prefs::Preferences;
 
 use crate::pipeline::UnprivilegedPipelineContent;
 use crate::serviceworker::ServiceWorkerUnprivilegedContent;
@@ -43,7 +42,7 @@ impl UnprivilegedContent {
         }
     }
 
-    pub fn prefs(&self) -> HashMap<String, PrefValue> {
+    pub fn prefs(&self) -> &Preferences {
         match self {
             UnprivilegedContent::Pipeline(content) => content.prefs(),
             UnprivilegedContent::ServiceWorker(content) => content.prefs(),
diff --git a/components/constellation/serviceworker.rs b/components/constellation/serviceworker.rs
index 9db6a8d8281..c4b13d7dbff 100644
--- a/components/constellation/serviceworker.rs
+++ b/components/constellation/serviceworker.rs
@@ -2,13 +2,12 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use std::collections::HashMap;
-
 use ipc_channel::Error;
 use script_traits::{SWManagerSenders, ServiceWorkerManagerFactory};
 use serde::{Deserialize, Serialize};
 use servo_config::opts::{self, Opts};
-use servo_config::prefs::{self, PrefValue};
+use servo_config::prefs;
+use servo_config::prefs::Preferences;
 use servo_url::ImmutableOrigin;
 
 use crate::sandboxing::{spawn_multiprocess, UnprivilegedContent};
@@ -18,7 +17,7 @@ use crate::sandboxing::{spawn_multiprocess, UnprivilegedContent};
 #[derive(Deserialize, Serialize)]
 pub struct ServiceWorkerUnprivilegedContent {
     opts: Opts,
-    prefs: HashMap<String, PrefValue>,
+    prefs: Box<Preferences>,
     senders: SWManagerSenders,
     origin: ImmutableOrigin,
 }
@@ -30,7 +29,7 @@ impl ServiceWorkerUnprivilegedContent {
     ) -> ServiceWorkerUnprivilegedContent {
         ServiceWorkerUnprivilegedContent {
             opts: (*opts::get()).clone(),
-            prefs: prefs::pref_map().iter().collect(),
+            prefs: Box::new(prefs::get().clone()),
             senders,
             origin,
         }
@@ -53,7 +52,7 @@ impl ServiceWorkerUnprivilegedContent {
         self.opts.clone()
     }
 
-    pub fn prefs(&self) -> HashMap<String, PrefValue> {
-        self.prefs.clone()
+    pub fn prefs(&self) -> &Preferences {
+        &self.prefs
     }
 }
diff --git a/components/devtools/actors/preference.rs b/components/devtools/actors/preference.rs
index 10bb402cc2f..bb48057e0da 100644
--- a/components/devtools/actors/preference.rs
+++ b/components/devtools/actors/preference.rs
@@ -2,14 +2,12 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use std::collections::HashMap;
 use std::net::TcpStream;
 
 use log::warn;
 use serde::Serialize;
 use serde_json::{Map, Value};
-use servo_config::pref_util::PrefValue;
-use servo_config::prefs::pref_map;
+use servo_config::pref;
 
 use crate::actor::{Actor, ActorMessageStatus, ActorRegistry};
 use crate::protocol::JsonPacketStream;
@@ -38,128 +36,93 @@ impl Actor for PreferenceActor {
         stream: &mut TcpStream,
         _id: StreamId,
     ) -> Result<ActorMessageStatus, ()> {
-        let Some(mut key) = msg.get("value").and_then(|v| v.as_str()) else {
+        let Some(key) = msg.get("value").and_then(|v| v.as_str()) else {
             warn!("PreferenceActor: handle_message: value is not a string");
             return Ok(ActorMessageStatus::Ignored);
         };
 
-        // Mapping to translate a Firefox preference name onto the corresponding Servo preference name
-        let pref_name_mapping: HashMap<&str, &str> =
-            [("dom.serviceWorkers.enabled", "dom.serviceworker.enabled")]
-                .iter()
-                .copied()
-                .collect();
-        if pref_name_mapping.contains_key(key) {
-            key = pref_name_mapping.get(key).unwrap();
-        }
-
-        let pref_value = pref_map().get(key);
-        Ok(handle_preference_value(
-            pref_value,
-            self.name(),
-            msg_type,
-            stream,
-        ))
+        // TODO: Map more preferences onto their Servo values.
+        Ok(match key {
+            "dom.serviceWorkers.enabled" => {
+                self.write_bool(pref!(dom_serviceworker_enabled), stream)
+            },
+            _ => self.handle_missing_preference(msg_type, stream),
+        })
     }
 }
 
-fn handle_preference_value(
-    pref_value: PrefValue,
-    name: String,
-    msg_type: &str,
-    stream: &mut TcpStream,
-) -> ActorMessageStatus {
-    match pref_value {
-        PrefValue::Float(value) => {
-            let reply = FloatReply { from: name, value };
-            let _ = stream.write_json_packet(&reply);
-            ActorMessageStatus::Processed
-        },
-        PrefValue::Int(value) => {
-            let reply = IntReply { from: name, value };
-            let _ = stream.write_json_packet(&reply);
-            ActorMessageStatus::Processed
-        },
-        PrefValue::Str(value) => {
-            let reply = CharReply { from: name, value };
-            let _ = stream.write_json_packet(&reply);
-            ActorMessageStatus::Processed
-        },
-        PrefValue::Bool(value) => {
-            let reply = BoolReply { from: name, value };
-            let _ = stream.write_json_packet(&reply);
-            ActorMessageStatus::Processed
-        },
-        PrefValue::Array(values) => {
-            let mut result = ActorMessageStatus::Processed;
-            for value in values {
-                result = handle_preference_value(value, name.clone(), msg_type, stream);
-            }
-            result
-        },
-        PrefValue::Missing => handle_missing_preference(name, msg_type, stream),
+impl PreferenceActor {
+    fn handle_missing_preference(
+        &self,
+        msg_type: &str,
+        stream: &mut TcpStream,
+    ) -> ActorMessageStatus {
+        match msg_type {
+            "getBoolPref" => self.write_bool(false, stream),
+            "getCharPref" => self.write_char("".into(), stream),
+            "getIntPref" => self.write_int(0, stream),
+            "getFloatPref" => self.write_float(0., stream),
+            _ => ActorMessageStatus::Ignored,
+        }
     }
-}
 
-// if the preferences are missing from pref_map then we return a
-// fake preference response based on msg_type.
-fn handle_missing_preference(
-    name: String,
-    msg_type: &str,
-    stream: &mut TcpStream,
-) -> ActorMessageStatus {
-    match msg_type {
-        "getBoolPref" => {
-            let reply = BoolReply {
-                from: name,
-                value: false,
-            };
-            let _ = stream.write_json_packet(&reply);
-            ActorMessageStatus::Processed
-        },
-
-        "getCharPref" => {
-            let reply = CharReply {
-                from: name,
-                value: "".to_owned(),
-            };
-            let _ = stream.write_json_packet(&reply);
-            ActorMessageStatus::Processed
-        },
-
-        "getIntPref" => {
-            let reply = IntReply {
-                from: name,
-                value: 0,
-            };
-            let _ = stream.write_json_packet(&reply);
-            ActorMessageStatus::Processed
-        },
-
-        _ => ActorMessageStatus::Ignored,
+    fn write_bool(&self, pref_value: bool, stream: &mut TcpStream) -> ActorMessageStatus {
+        #[derive(Serialize)]
+        struct BoolReply {
+            from: String,
+            value: bool,
+        }
+
+        let reply = BoolReply {
+            from: self.name.clone(),
+            value: pref_value,
+        };
+        let _ = stream.write_json_packet(&reply);
+        ActorMessageStatus::Processed
     }
-}
 
-#[derive(Serialize)]
-struct BoolReply {
-    from: String,
-    value: bool,
-}
+    fn write_char(&self, pref_value: String, stream: &mut TcpStream) -> ActorMessageStatus {
+        #[derive(Serialize)]
+        struct CharReply {
+            from: String,
+            value: String,
+        }
 
-#[derive(Serialize)]
-struct CharReply {
-    from: String,
-    value: String,
-}
+        let reply = CharReply {
+            from: self.name.clone(),
+            value: pref_value,
+        };
+        let _ = stream.write_json_packet(&reply);
+        ActorMessageStatus::Processed
+    }
 
-#[derive(Serialize)]
-struct IntReply {
-    from: String,
-    value: i64,
-}
+    fn write_int(&self, pref_value: i64, stream: &mut TcpStream) -> ActorMessageStatus {
+        #[derive(Serialize)]
+        struct IntReply {
+            from: String,
+            value: i64,
+        }
 
-#[derive(Serialize)]
-struct FloatReply {
-    from: String,
-    value: f64,
+        let reply = IntReply {
+            from: self.name.clone(),
+            value: pref_value,
+        };
+        let _ = stream.write_json_packet(&reply);
+        ActorMessageStatus::Processed
+    }
+
+    fn write_float(&self, pref_value: f64, stream: &mut TcpStream) -> ActorMessageStatus {
+        #[derive(Serialize)]
+        struct FloatReply {
+            from: String,
+            value: f64,
+        }
+
+        let reply = FloatReply {
+            from: self.name.clone(),
+            value: pref_value,
+        };
+        let _ = stream.write_json_packet(&reply);
+        ActorMessageStatus::Processed
+    }
 }
diff --git a/components/fonts/system_font_service.rs b/components/fonts/system_font_service.rs
index 42acc5ab85b..b29eca6b86c 100644
--- a/components/fonts/system_font_service.rs
+++ b/components/fonts/system_font_service.rs
@@ -323,10 +323,10 @@ impl SystemFontService {
             .get_or_init(|| {
                 // First check whether the font is set in the preferences.
                 let family_name = match generic {
-                    GenericFontFamily::None => pref!(fonts.default),
-                    GenericFontFamily::Serif => pref!(fonts.serif),
-                    GenericFontFamily::SansSerif => pref!(fonts.sans_serif),
-                    GenericFontFamily::Monospace => pref!(fonts.monospace),
+                    GenericFontFamily::None => pref!(fonts_default),
+                    GenericFontFamily::Serif => pref!(fonts_serif),
+                    GenericFontFamily::SansSerif => pref!(fonts_sans_serif),
+                    GenericFontFamily::Monospace => pref!(fonts_monospace),
                     _ => String::new(),
                 };
 
diff --git a/components/layout_thread/lib.rs b/components/layout_thread/lib.rs
index 1a5630293b3..d0eae9afb45 100644
--- a/components/layout_thread/lib.rs
+++ b/components/layout_thread/lib.rs
@@ -520,7 +520,7 @@ impl LayoutThread {
         compositor_api.send_initial_transaction(id.into());
 
         let mut font = Font::initial_values();
-        let default_font_size = pref!(fonts.default_size);
+        let default_font_size = pref!(fonts_default_size);
         font.font_size = FontSize {
             computed_size: NonNegativeLength::new(default_font_size as f32),
             used_size: NonNegativeLength::new(default_font_size as f32),
@@ -1519,8 +1519,8 @@ impl FontMetricsProvider for LayoutFontMetricsProvider {
 
     fn base_size_for_generic(&self, generic: GenericFontFamily) -> Length {
         Length::new(match generic {
-            GenericFontFamily::Monospace => pref!(fonts.default_monospace_size),
-            _ => pref!(fonts.default_size),
+            GenericFontFamily::Monospace => pref!(fonts_default_monospace_size),
+            _ => pref!(fonts_default_size),
         } as f32)
         .max(Length::new(0.0))
     }
diff --git a/components/layout_thread_2020/lib.rs b/components/layout_thread_2020/lib.rs
index 496e15b16ee..85d499ecfde 100644
--- a/components/layout_thread_2020/lib.rs
+++ b/components/layout_thread_2020/lib.rs
@@ -495,7 +495,7 @@ impl LayoutThread {
         compositor_api.send_initial_transaction(id.into());
 
         let mut font = Font::initial_values();
-        let default_font_size = pref!(fonts.default_size);
+        let default_font_size = pref!(fonts_default_size);
         font.font_size = FontSize {
             computed_size: NonNegativeLength::new(default_font_size as f32),
             used_size: NonNegativeLength::new(default_font_size as f32),
@@ -1232,8 +1232,8 @@ impl FontMetricsProvider for LayoutFontMetricsProvider {
 
     fn base_size_for_generic(&self, generic: GenericFontFamily) -> Length {
         Length::new(match generic {
-            GenericFontFamily::Monospace => pref!(fonts.default_monospace_size),
-            _ => pref!(fonts.default_size),
+            GenericFontFamily::Monospace => pref!(fonts_default_monospace_size),
+            _ => pref!(fonts_default_size),
         } as f32)
         .max(Length::new(0.0))
     }
diff --git a/components/net/async_runtime.rs b/components/net/async_runtime.rs
index 7d1fb9daeaa..c99068b1076 100644
--- a/components/net/async_runtime.rs
+++ b/components/net/async_runtime.rs
@@ -19,9 +19,9 @@ pub static HANDLE: LazyLock<Mutex<Option<Runtime>>> = LazyLock::new(|| {
             .worker_threads(
                 thread::available_parallelism()
                     .map(|i| i.get())
-                    .unwrap_or(servo_config::pref!(threadpools.fallback_worker_num) as usize)
+                    .unwrap_or(servo_config::pref!(threadpools_fallback_worker_num) as usize)
                     .min(
-                        servo_config::pref!(threadpools.async_runtime_workers.max).max(1) as usize,
+                        servo_config::pref!(threadpools_async_runtime_workers_max).max(1) as usize,
                     ),
             )
             .enable_io()
diff --git a/components/net/decoder.rs b/components/net/decoder.rs
index 9b6c8f1a3d0..4d0973cdac2 100644
--- a/components/net/decoder.rs
+++ b/components/net/decoder.rs
@@ -280,7 +280,7 @@ impl Stream for BodyStream {
                     .content_length
                     .map_or(false, |c| c.0 == self.total_read);
                 if self.is_secure_scheme &&
-                    (all_content_read || pref!(network.tls.ignore_unexpected_eof))
+                    (all_content_read || pref!(network_tls_ignore_unexpected_eof))
                 {
                     let source = err.source();
                     let is_unexpected_eof = source
diff --git a/components/net/filemanager_thread.rs b/components/net/filemanager_thread.rs
index e72290b2694..65c3736bf24 100644
--- a/components/net/filemanager_thread.rs
+++ b/components/net/filemanager_thread.rs
@@ -602,7 +602,7 @@ impl FileManagerStore {
         // Check if the select_files preference is enabled
         // to ensure process-level security against compromised script;
         // Then try applying opt_test_path directly for testing convenience
-        let opt_s = if pref!(dom.testing.html_input_element.select_files.enabled) {
+        let opt_s = if pref!(dom_testing_html_input_element_select_files_enabled) {
             opt_test_path
         } else {
             self.query_files_from_embedder(patterns, false, embedder_proxy)
@@ -632,7 +632,7 @@ impl FileManagerStore {
         // Check if the select_files preference is enabled
         // to ensure process-level security against compromised script;
         // Then try applying opt_test_paths directly for testing convenience
-        let opt_v = if pref!(dom.testing.html_input_element.select_files.enabled) {
+        let opt_v = if pref!(dom_testing_html_input_element_select_files_enabled) {
             opt_test_paths
         } else {
             self.query_files_from_embedder(patterns, true, embedder_proxy)
diff --git a/components/net/hsts.rs b/components/net/hsts.rs
index ebaf6e783bd..da57051790f 100644
--- a/components/net/hsts.rs
+++ b/components/net/hsts.rs
@@ -144,8 +144,8 @@ impl HstsList {
             return;
         }
 
-        let upgrade_scheme = if pref!(network.enforce_tls.enabled) {
-            if (!pref!(network.enforce_tls.localhost) &&
+        let upgrade_scheme = if pref!(network_enforce_tls_enabled) {
+            if (!pref!(network_enforce_tls_localhost) &&
                 match url.host() {
                     Some(Host::Domain(domain)) => {
                         domain.ends_with(".localhost") || domain == "localhost"
@@ -154,7 +154,7 @@ impl HstsList {
                     Some(Host::Ipv6(ipv6)) => ipv6.is_loopback(),
                     _ => false,
                 }) ||
-                (!pref!(network.enforce_tls.onion) &&
+                (!pref!(network_enforce_tls_onion) &&
                     url.domain()
                         .is_some_and(|domain| domain.ends_with(".onion")))
             {
diff --git a/components/net/http_cache.rs b/components/net/http_cache.rs
index bf6d28de220..0f0f715b3f6 100644
--- a/components/net/http_cache.rs
+++ b/components/net/http_cache.rs
@@ -756,7 +756,7 @@ impl HttpCache {
     /// Storing Responses in Caches.
     /// <https://tools.ietf.org/html/rfc7234#section-3>
     pub fn store(&mut self, request: &Request, response: &Response) {
-        if pref!(network.http_cache.disabled) {
+        if pref!(network_http_cache_disabled) {
             return;
         }
         if request.method != Method::GET {
diff --git a/components/net/image_cache.rs b/components/net/image_cache.rs
index 3d2ffcf5706..a9a6e558919 100644
--- a/components/net/image_cache.rs
+++ b/components/net/image_cache.rs
@@ -17,6 +17,7 @@ use net_traits::image_cache::{
 use net_traits::request::CorsSettings;
 use net_traits::{FetchMetadata, FetchResponseMsg, FilteredMetadata, NetworkError};
 use pixels::{load_from_memory, CorsStatus, Image, ImageMetadata, PixelFormat};
+use servo_config::pref;
 use servo_url::{ImmutableOrigin, ServoUrl};
 use webrender_api::units::DeviceIntSize;
 use webrender_api::{ImageDescriptor, ImageDescriptorFlags, ImageFormat};
@@ -422,8 +423,8 @@ impl ImageCache for ImageCacheImpl {
         // If no information can be obtained about the system, uses 4 threads as a default
         let thread_count = thread::available_parallelism()
             .map(|i| i.get())
-            .unwrap_or(servo_config::pref!(threadpools.fallback_worker_num) as usize)
-            .min(servo_config::pref!(threadpools.async_runtime_workers.max).max(1) as usize);
+            .unwrap_or(pref!(threadpools_fallback_worker_num) as usize)
+            .min(pref!(threadpools_async_runtime_workers_max).max(1) as usize);
 
         ImageCacheImpl {
             store: Arc::new(Mutex::new(ImageCacheStore {
diff --git a/components/net/local_directory_listing.rs b/components/net/local_directory_listing.rs
index 39e6a98d66c..ab89e054b20 100644
--- a/components/net/local_directory_listing.rs
+++ b/components/net/local_directory_listing.rs
@@ -16,7 +16,7 @@ use servo_url::ServoUrl;
 use url::Url;
 
 pub fn fetch(request: &mut Request, url: ServoUrl, path_buf: PathBuf) -> Response {
-    if !pref!(network.local_directory_listing.enabled) {
+    if !pref!(network_local_directory_listing_enabled) {
         // If you want to be able to browse local directories, configure Servo prefs so that
         // "network.local_directory_listing.enabled" is set to true.
         return Response::network_error(NetworkError::Internal(
diff --git a/components/net/resource_thread.rs b/components/net/resource_thread.rs
index 2001faccd22..12278d4c326 100644
--- a/components/net/resource_thread.rs
+++ b/components/net/resource_thread.rs
@@ -695,8 +695,8 @@ impl CoreResourceManager {
     ) -> CoreResourceManager {
         let num_threads = thread::available_parallelism()
             .map(|i| i.get())
-            .unwrap_or(servo_config::pref!(threadpools.fallback_worker_num) as usize)
-            .min(servo_config::pref!(threadpools.resource_workers.max).max(1) as usize);
+            .unwrap_or(servo_config::pref!(threadpools_fallback_worker_num) as usize)
+            .min(servo_config::pref!(threadpools_resource_workers_max).max(1) as usize);
         let pool = CoreResourceThreadPool::new(num_threads, "CoreResourceThreadPool".to_string());
         let pool_handle = Arc::new(pool);
         CoreResourceManager {
diff --git a/components/net/tests/filemanager_thread.rs b/components/net/tests/filemanager_thread.rs
index 9a1b33becec..0e3e8aeb91a 100644
--- a/components/net/tests/filemanager_thread.rs
+++ b/components/net/tests/filemanager_thread.rs
@@ -15,16 +15,19 @@ use net_traits::blob_url_store::BlobURLStoreError;
 use net_traits::filemanager_thread::{
     FileManagerThreadError, FileManagerThreadMsg, ReadFileProgress,
 };
-use servo_config::set_pref;
+use servo_config::prefs::Preferences;
 
 use crate::create_embedder_proxy;
 
 #[test]
 fn test_filemanager() {
+    let mut preferences = Preferences::default();
+    preferences.dom_testing_html_input_element_select_files_enabled = true;
+    servo_config::prefs::set(preferences);
+
     let pool = CoreResourceThreadPool::new(1, "CoreResourceTestPool".to_string());
     let pool_handle = Arc::new(pool);
     let filemanager = FileManager::new(create_embedder_proxy(), Arc::downgrade(&pool_handle));
-    set_pref!(dom.testing.html_input_element.select_files.enabled, true);
 
     // Try to open a dummy file "components/net/tests/test.jpeg" in tree
     let mut handler = File::open("tests/test.jpeg").expect("test.jpeg is stolen");
diff --git a/components/script/dom/bindings/codegen/run.py b/components/script/dom/bindings/codegen/run.py
index 2dee39814b2..d60cff896da 100644
--- a/components/script/dom/bindings/codegen/run.py
+++ b/components/script/dom/bindings/codegen/run.py
@@ -89,10 +89,31 @@ def generate(config, name, filename):
 
 
 def add_css_properties_attributes(css_properties_json, parser):
+    def map_preference_name(preference_name: str):
+        """Map between Stylo preference names and Servo preference names as the
+        `css-properties.json` file is generated by Stylo. This should be kept in sync with the
+        preference mapping done in `components/servo_config/prefs.rs`, which handles the runtime version of
+        these preferences."""
+        MAPPING = [
+            ["layout.unimplemented", "layout_unimplemented"],
+            ["layout.threads", "layout_threads"],
+            ["layout.legacy_layout", "layout_legacy_layout"],
+            ["layout.flexbox.enabled", "layout_flexbox_enabled"],
+            ["layout.columns.enabled", "layout_columns_enabled"],
+            ["layout.grid.enabled", "layout_grid_enabled"],
+            ["layout.css.transition-behavior.enabled", "layout_css_transition_behavior_enabled"],
+            ["layout.writing-mode.enabled", "layout_writing_mode_enabled"],
+            ["layout.container-queries.enabled", "layout_container_queries_enabled"],
+        ]
+        for mapping in MAPPING:
+            if mapping[0] == preference_name:
+                return mapping[1]
+        return preference_name
+
     css_properties = json.load(open(css_properties_json, "rb"))
     idl = "partial interface CSSStyleDeclaration {\n%s\n};\n" % "\n".join(
         "  [%sCEReactions, SetterThrows] attribute [LegacyNullToEmptyString] DOMString %s;" % (
-            ('Pref="%s", ' % data["pref"] if data["pref"] else ""),
+            (f'Pref="{map_preference_name(data["pref"])}", ' if data["pref"] else ""),
             attribute_name
         )
         for (kind, properties_list) in sorted(css_properties.items())
diff --git a/components/script/dom/bindings/guard.rs b/components/script/dom/bindings/guard.rs
index 45e4473d821..fb2b2ebc807 100644
--- a/components/script/dom/bindings/guard.rs
+++ b/components/script/dom/bindings/guard.rs
@@ -5,7 +5,7 @@
 //! Machinery to conditionally expose things.
 
 use js::rust::HandleObject;
-use servo_config::prefs;
+use servo_config::prefs::get;
 
 use crate::dom::bindings::codegen::InterfaceObjectMap;
 use crate::dom::bindings::interface::is_exposed_in;
@@ -85,7 +85,7 @@ impl Condition {
         global: HandleObject,
     ) -> bool {
         match *self {
-            Condition::Pref(name) => prefs::pref_map().get(name).as_bool().unwrap_or(false),
+            Condition::Pref(name) => get().get_value(name).try_into().unwrap_or(false),
             Condition::Func(f) => f(cx, obj),
             Condition::Exposed(globals) => is_exposed_in(global, globals),
             Condition::SecureContext() => is_secure_context(cx),
diff --git a/components/script/dom/create.rs b/components/script/dom/create.rs
index 7f3dfdac540..cde5bcbb13f 100644
--- a/components/script/dom/create.rs
+++ b/components/script/dom/create.rs
@@ -108,7 +108,7 @@ fn create_svg_element(
         })
     );
 
-    if !pref!(dom.svg.enabled) {
+    if !pref!(dom_svg_enabled) {
         return Element::new(name.local, name.ns, prefix, document, proto, CanGc::note());
     }
 
diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index 11602547b7e..11a0c0935cd 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -1356,8 +1356,8 @@ impl Document {
 
         if let Some((last_time, last_pos)) = opt {
             let DBL_CLICK_TIMEOUT =
-                Duration::from_millis(pref!(dom.document.dblclick_timeout) as u64);
-            let DBL_CLICK_DIST_THRESHOLD = pref!(dom.document.dblclick_dist) as u64;
+                Duration::from_millis(pref!(dom_document_dblclick_timeout) as u64);
+            let DBL_CLICK_DIST_THRESHOLD = pref!(dom_document_dblclick_dist) as u64;
 
             // Calculate distance between this click and the previous click.
             let line = click_pos - last_pos;
@@ -2469,7 +2469,7 @@ impl Document {
         // https://immersive-web.github.io/webxr/#user-intention
         // https://github.com/immersive-web/navigation/issues/10
         #[cfg(feature = "webxr")]
-        if pref!(dom.webxr.sessionavailable) && self.window.is_top_level() {
+        if pref!(dom_webxr_sessionavailable) && self.window.is_top_level() {
             self.window.Navigator().Xr().dispatch_sessionavailable();
         }
 
@@ -2850,7 +2850,7 @@ impl Document {
         local_name: &LocalName,
         is: Option<&LocalName>,
     ) -> Option<Rc<CustomElementDefinition>> {
-        if !pref!(dom.custom_elements.enabled) {
+        if !pref!(dom_customelements_enabled) {
             return None;
         }
 
@@ -3344,7 +3344,7 @@ impl Document {
             #[cfg(feature = "webgpu")]
             webgpu_contexts: Rc::new(RefCell::new(HashMapTracedValues::new())),
             selection: MutNullableDom::new(None),
-            animation_timeline: if pref!(layout.animations.test.enabled) {
+            animation_timeline: if pref!(layout_animations_test_enabled) {
                 DomRefCell::new(AnimationTimeline::new_for_testing())
             } else {
                 DomRefCell::new(AnimationTimeline::new())
@@ -3826,7 +3826,7 @@ impl Document {
             error = true;
         }
 
-        if pref!(dom.fullscreen.test) {
+        if pref!(dom_fullscreen_test) {
             // For reftests we just take over the current window,
             // and don't try to really enter fullscreen.
             info!("Tests don't really enter fullscreen.");
@@ -4109,7 +4109,7 @@ impl Document {
     /// An implementation of <https://drafts.csswg.org/web-animations-1/#update-animations-and-send-events>.
     pub(crate) fn update_animations_and_send_events(&self, can_gc: CanGc) {
         // Only update the time if it isn't being managed by a test.
-        if !pref!(layout.animations.test.enabled) {
+        if !pref!(layout_animations_test_enabled) {
             self.animation_timeline.borrow_mut().update();
         }
 
diff --git a/components/script/dom/htmlmediaelement.rs b/components/script/dom/htmlmediaelement.rs
index 22fb9084189..704ec00f45c 100644
--- a/components/script/dom/htmlmediaelement.rs
+++ b/components/script/dom/htmlmediaelement.rs
@@ -1325,7 +1325,7 @@ impl HTMLMediaElement {
             .render_poster_frame(image);
         self.upcast::<Node>().dirty(NodeDamage::OtherNodeDamage);
 
-        if pref!(media.testing.enabled) {
+        if pref!(media_testing_enabled) {
             self.owner_global()
                 .task_manager()
                 .media_element_task_source()
diff --git a/components/script/dom/htmlscriptelement.rs b/components/script/dom/htmlscriptelement.rs
index b0d8d5ab47b..c76075a93aa 100644
--- a/components/script/dom/htmlscriptelement.rs
+++ b/components/script/dom/htmlscriptelement.rs
@@ -463,7 +463,7 @@ impl FetchResponseListener for ClassicContext {
         /*
         let options = unsafe { CompileOptionsWrapper::new(*cx, final_url.as_str(), 1) };
 
-        let can_compile_off_thread = pref!(dom.script.asynch) &&
+        let can_compile_off_thread = pref!(dom_script_asynch) &&
             unsafe { CanCompileOffThread(*cx, options.ptr as *const _, source_text.len()) };
 
         if can_compile_off_thread {
diff --git a/components/script/dom/mouseevent.rs b/components/script/dom/mouseevent.rs
index 1d616c5f1ab..7d2a51bc8f7 100644
--- a/components/script/dom/mouseevent.rs
+++ b/components/script/dom/mouseevent.rs
@@ -408,7 +408,7 @@ impl MouseEventMethods<crate::DomTypeHolder> for MouseEvent {
     // This returns the same result as current gecko.
     // https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/which
     fn Which(&self) -> i32 {
-        if pref!(dom.mouse_event.which.enabled) {
+        if pref!(dom_mouse_event_which_enabled) {
             (self.button.get() + 1) as i32
         } else {
             0
diff --git a/components/script/dom/paintworkletglobalscope.rs b/components/script/dom/paintworkletglobalscope.rs
index b806927a9b9..b971bbbd35f 100644
--- a/components/script/dom/paintworkletglobalscope.rs
+++ b/components/script/dom/paintworkletglobalscope.rs
@@ -421,7 +421,7 @@ impl PaintWorkletGlobalScope {
                     .expect("Locking a painter.")
                     .schedule_a_worklet_task(WorkletTask::Paint(task));
 
-                let timeout = pref!(dom.worklet.timeout_ms) as u64;
+                let timeout = pref!(dom_worklet_timeout_ms) as u64;
 
                 receiver
                     .recv_timeout(Duration::from_millis(timeout))
diff --git a/components/script/dom/permissions.rs b/components/script/dom/permissions.rs
index badadb9b0ee..8efa1b09765 100644
--- a/components/script/dom/permissions.rs
+++ b/components/script/dom/permissions.rs
@@ -301,7 +301,7 @@ pub(crate) fn get_descriptor_permission_state(
     // and let the user decide to grant the permission or not.
     let state = if allowed_in_nonsecure_contexts(&permission_name) {
         PermissionState::Prompt
-    } else if pref!(dom.permissions.testing.allowed_in_nonsecure_contexts) {
+    } else if pref!(dom_permissions_testing_allowed_in_nonsecure_contexts) {
         PermissionState::Granted
     } else {
         globalscope
diff --git a/components/script/dom/serviceworkerglobalscope.rs b/components/script/dom/serviceworkerglobalscope.rs
index 870940d0609..aa9184a3dc9 100644
--- a/components/script/dom/serviceworkerglobalscope.rs
+++ b/components/script/dom/serviceworkerglobalscope.rs
@@ -306,7 +306,7 @@ impl ServiceWorkerGlobalScope {
 
                 // Service workers are time limited
                 // https://w3c.github.io/ServiceWorker/#service-worker-lifetime
-                let sw_lifetime_timeout = pref!(dom.serviceworker.timeout_seconds) as u64;
+                let sw_lifetime_timeout = pref!(dom_serviceworker_timeout_seconds) as u64;
                 let time_out_port = after(Duration::new(sw_lifetime_timeout, 0));
 
                 let (devtools_mpsc_chan, devtools_mpsc_port) = unbounded();
diff --git a/components/script/dom/servoparser/mod.rs b/components/script/dom/servoparser/mod.rs
index 18a7aed45f0..fe9719f5569 100644
--- a/components/script/dom/servoparser/mod.rs
+++ b/components/script/dom/servoparser/mod.rs
@@ -158,7 +158,7 @@ impl ServoParser {
         url: ServoUrl,
         can_gc: CanGc,
     ) {
-        let parser = if pref!(dom.servoparser.async_html_tokenizer.enabled) {
+        let parser = if pref!(dom_servoparser_async_html_tokenizer_enabled) {
             ServoParser::new(
                 document,
                 Tokenizer::AsyncHtml(self::async_html::Tokenizer::new(document, url, None)),
diff --git a/components/script/dom/testbinding.rs b/components/script/dom/testbinding.rs
index 9e3aa7749c6..0677623ea36 100644
--- a/components/script/dom/testbinding.rs
+++ b/components/script/dom/testbinding.rs
@@ -880,17 +880,18 @@ impl TestBindingMethods<crate::DomTypeHolder> for TestBinding {
     fn PassVariadicAny(&self, _: SafeJSContext, _: Vec<HandleValue>) {}
     fn PassVariadicObject(&self, _: SafeJSContext, _: Vec<*mut JSObject>) {}
     fn BooleanMozPreference(&self, pref_name: DOMString) -> bool {
-        prefs::pref_map()
-            .get(pref_name.as_ref())
-            .as_bool()
+        prefs::get()
+            .get_value(pref_name.as_ref())
+            .try_into()
             .unwrap_or(false)
     }
     fn StringMozPreference(&self, pref_name: DOMString) -> DOMString {
-        prefs::pref_map()
-            .get(pref_name.as_ref())
-            .as_str()
-            .map(DOMString::from)
-            .unwrap_or_default()
+        DOMString::from_string(
+            prefs::get()
+                .get_value(pref_name.as_ref())
+                .try_into()
+                .unwrap_or_default(),
+        )
     }
     fn PrefControlledAttributeDisabled(&self) -> bool {
         false
diff --git a/components/script/dom/webgl2renderingcontext.rs b/components/script/dom/webgl2renderingcontext.rs
index c351f025245..db81983c106 100644
--- a/components/script/dom/webgl2renderingcontext.rs
+++ b/components/script/dom/webgl2renderingcontext.rs
@@ -198,7 +198,7 @@ impl WebGL2RenderingContext {
 
     #[allow(unsafe_code)]
     pub(crate) fn is_webgl2_enabled(_cx: JSContext, global: HandleObject) -> bool {
-        if pref!(dom.webgl2.enabled) {
+        if pref!(dom_webgl2_enabled) {
             return true;
         }
 
diff --git a/components/script/dom/webglrenderingcontext.rs b/components/script/dom/webglrenderingcontext.rs
index 0b8e53f5961..1ca324baaab 100644
--- a/components/script/dom/webglrenderingcontext.rs
+++ b/components/script/dom/webglrenderingcontext.rs
@@ -222,7 +222,7 @@ impl WebGLRenderingContext {
         size: Size2D<u32>,
         attrs: GLContextAttributes,
     ) -> Result<WebGLRenderingContext, String> {
-        if pref!(webgl.testing.context_creation_error) {
+        if pref!(webgl_testing_context_creation_error) {
             return Err("WebGL context creation error forced by pref `webgl.testing.context_creation_error`".into());
         }
 
diff --git a/components/script/dom/webidls/AbortController.webidl b/components/script/dom/webidls/AbortController.webidl
index faeaf9cbd44..cef49010d3c 100644
--- a/components/script/dom/webidls/AbortController.webidl
+++ b/components/script/dom/webidls/AbortController.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://dom.spec.whatwg.org/#interface-abortcontroller
-[Exposed=*, Pref="dom.abort_controller.enabled"]
+[Exposed=*, Pref="dom_abort_controller_enabled"]
 interface AbortController {
   constructor();
 
diff --git a/components/script/dom/webidls/ActivatableElement.webidl b/components/script/dom/webidls/ActivatableElement.webidl
index e9d959c8470..99a250a4b55 100644
--- a/components/script/dom/webidls/ActivatableElement.webidl
+++ b/components/script/dom/webidls/ActivatableElement.webidl
@@ -7,9 +7,9 @@
 // web pages.
 [Exposed=(Window,Worker)]
 interface mixin ActivatableElement {
-  [Throws, Pref="dom.testing.element.activation.enabled"]
+  [Throws, Pref="dom_testing_element_activation_enabled"]
   undefined enterFormalActivationState();
 
-  [Throws, Pref="dom.testing.element.activation.enabled"]
+  [Throws, Pref="dom_testing_element_activation_enabled"]
   undefined exitFormalActivationState();
 };
diff --git a/components/script/dom/webidls/Bluetooth.webidl b/components/script/dom/webidls/Bluetooth.webidl
index e5e135c0577..65ce8ea79b3 100644
--- a/components/script/dom/webidls/Bluetooth.webidl
+++ b/components/script/dom/webidls/Bluetooth.webidl
@@ -25,7 +25,7 @@ dictionary RequestDeviceOptions {
   boolean acceptAllDevices = false;
 };
 
-[Exposed=Window, Pref="dom.bluetooth.enabled"]
+[Exposed=Window, Pref="dom_bluetooth_enabled"]
 interface Bluetooth : EventTarget {
   [SecureContext]
   Promise<boolean> getAvailability();
diff --git a/components/script/dom/webidls/BluetoothAdvertisingEvent.webidl b/components/script/dom/webidls/BluetoothAdvertisingEvent.webidl
index a7dd3fe947f..c6f3c6a8480 100644
--- a/components/script/dom/webidls/BluetoothAdvertisingEvent.webidl
+++ b/components/script/dom/webidls/BluetoothAdvertisingEvent.webidl
@@ -10,7 +10,7 @@
 interface BluetoothServiceDataMap {
   readonly maplike<UUID, DataView>;
 };*/
-[Exposed=Window, Pref="dom.bluetooth.enabled"]
+[Exposed=Window, Pref="dom_bluetooth_enabled"]
 interface BluetoothAdvertisingEvent : Event {
   [Throws] constructor(DOMString type, BluetoothAdvertisingEventInit init);
   [SameObject]
diff --git a/components/script/dom/webidls/BluetoothCharacteristicProperties.webidl b/components/script/dom/webidls/BluetoothCharacteristicProperties.webidl
index 124f881a2e0..fb812ff7c46 100644
--- a/components/script/dom/webidls/BluetoothCharacteristicProperties.webidl
+++ b/components/script/dom/webidls/BluetoothCharacteristicProperties.webidl
@@ -4,7 +4,7 @@
 
 // https://webbluetoothcg.github.io/web-bluetooth/#characteristicproperties
 
-[Exposed=Window, Pref="dom.bluetooth.enabled"]
+[Exposed=Window, Pref="dom_bluetooth_enabled"]
 interface BluetoothCharacteristicProperties {
   readonly attribute boolean broadcast;
   readonly attribute boolean read;
diff --git a/components/script/dom/webidls/BluetoothDevice.webidl b/components/script/dom/webidls/BluetoothDevice.webidl
index c514132140d..f9cb44dda5a 100644
--- a/components/script/dom/webidls/BluetoothDevice.webidl
+++ b/components/script/dom/webidls/BluetoothDevice.webidl
@@ -4,7 +4,7 @@
 
 // https://webbluetoothcg.github.io/web-bluetooth/#bluetoothdevice
 
-[Exposed=Window, Pref="dom.bluetooth.enabled"]
+[Exposed=Window, Pref="dom_bluetooth_enabled"]
 interface BluetoothDevice : EventTarget {
   readonly attribute DOMString id;
   readonly attribute DOMString? name;
diff --git a/components/script/dom/webidls/BluetoothPermissionResult.webidl b/components/script/dom/webidls/BluetoothPermissionResult.webidl
index 95c06797aef..67822fc55cf 100644
--- a/components/script/dom/webidls/BluetoothPermissionResult.webidl
+++ b/components/script/dom/webidls/BluetoothPermissionResult.webidl
@@ -12,7 +12,7 @@ dictionary BluetoothPermissionDescriptor : PermissionDescriptor {
   boolean acceptAllDevices = false;
 };
 
-[Exposed=Window, Pref="dom.bluetooth.enabled"]
+[Exposed=Window, Pref="dom_bluetooth_enabled"]
 interface BluetoothPermissionResult : PermissionStatus {
   // attribute FrozenArray<BluetoothDevice> devices;
   // Workaround until FrozenArray get implemented.
diff --git a/components/script/dom/webidls/BluetoothRemoteGATTCharacteristic.webidl b/components/script/dom/webidls/BluetoothRemoteGATTCharacteristic.webidl
index 9f41d2450f9..9e0140d8129 100644
--- a/components/script/dom/webidls/BluetoothRemoteGATTCharacteristic.webidl
+++ b/components/script/dom/webidls/BluetoothRemoteGATTCharacteristic.webidl
@@ -4,7 +4,7 @@
 
 // https://webbluetoothcg.github.io/web-bluetooth/#bluetoothremotegattcharacteristic
 
-[Exposed=Window, Pref="dom.bluetooth.enabled"]
+[Exposed=Window, Pref="dom_bluetooth_enabled"]
 interface BluetoothRemoteGATTCharacteristic : EventTarget {
   [SameObject]
   readonly attribute BluetoothRemoteGATTService service;
diff --git a/components/script/dom/webidls/BluetoothRemoteGATTDescriptor.webidl b/components/script/dom/webidls/BluetoothRemoteGATTDescriptor.webidl
index 29cbc3040a4..31e19a850fc 100644
--- a/components/script/dom/webidls/BluetoothRemoteGATTDescriptor.webidl
+++ b/components/script/dom/webidls/BluetoothRemoteGATTDescriptor.webidl
@@ -4,7 +4,7 @@
 
 // http://webbluetoothcg.github.io/web-bluetooth/#bluetoothremotegattdescriptor
 
-[Exposed=Window, Pref="dom.bluetooth.enabled"]
+[Exposed=Window, Pref="dom_bluetooth_enabled"]
 interface BluetoothRemoteGATTDescriptor {
   [SameObject]
   readonly attribute BluetoothRemoteGATTCharacteristic characteristic;
diff --git a/components/script/dom/webidls/BluetoothRemoteGATTServer.webidl b/components/script/dom/webidls/BluetoothRemoteGATTServer.webidl
index e46cef4a079..3d60ace070f 100644
--- a/components/script/dom/webidls/BluetoothRemoteGATTServer.webidl
+++ b/components/script/dom/webidls/BluetoothRemoteGATTServer.webidl
@@ -4,7 +4,7 @@
 
 //https://webbluetoothcg.github.io/web-bluetooth/#bluetoothremotegattserver
 
-[Exposed=Window, Pref="dom.bluetooth.enabled"]
+[Exposed=Window, Pref="dom_bluetooth_enabled"]
 interface BluetoothRemoteGATTServer {
   [SameObject]
   readonly attribute BluetoothDevice device;
diff --git a/components/script/dom/webidls/BluetoothRemoteGATTService.webidl b/components/script/dom/webidls/BluetoothRemoteGATTService.webidl
index 7e9f624dd1c..e505ae3aabe 100644
--- a/components/script/dom/webidls/BluetoothRemoteGATTService.webidl
+++ b/components/script/dom/webidls/BluetoothRemoteGATTService.webidl
@@ -4,7 +4,7 @@
 
 // https://webbluetoothcg.github.io/web-bluetooth/#bluetoothremotegattservice
 
-[Exposed=Window, Pref="dom.bluetooth.enabled"]
+[Exposed=Window, Pref="dom_bluetooth_enabled"]
 interface BluetoothRemoteGATTService : EventTarget {
   [SameObject]
   readonly attribute BluetoothDevice device;
diff --git a/components/script/dom/webidls/BluetoothUUID.webidl b/components/script/dom/webidls/BluetoothUUID.webidl
index dde82d3acb7..5ee501bf6e6 100644
--- a/components/script/dom/webidls/BluetoothUUID.webidl
+++ b/components/script/dom/webidls/BluetoothUUID.webidl
@@ -4,7 +4,7 @@
 
 // https://webbluetoothcg.github.io/web-bluetooth/#bluetoothuuid
 
-[Exposed=Window, Pref="dom.bluetooth.enabled"]
+[Exposed=Window, Pref="dom_bluetooth_enabled"]
 interface BluetoothUUID {
   [Throws]
   static UUID getService(BluetoothServiceUUID name);
diff --git a/components/script/dom/webidls/CSS.webidl b/components/script/dom/webidls/CSS.webidl
index 15049ae7539..2a199569cd8 100644
--- a/components/script/dom/webidls/CSS.webidl
+++ b/components/script/dom/webidls/CSS.webidl
@@ -20,5 +20,5 @@ partial interface CSS {
 
 // https://drafts.css-houdini.org/css-paint-api-1/#paint-worklet
 partial interface CSS {
-    [SameObject, Pref="dom.worklet.enabled"] static readonly attribute Worklet paintWorklet;
+    [SameObject, Pref="dom_worklet_enabled"] static readonly attribute Worklet paintWorklet;
 };
diff --git a/components/script/dom/webidls/CSSStyleValue.webidl b/components/script/dom/webidls/CSSStyleValue.webidl
index 3cd075b67e8..a87c2b29910 100644
--- a/components/script/dom/webidls/CSSStyleValue.webidl
+++ b/components/script/dom/webidls/CSSStyleValue.webidl
@@ -4,7 +4,7 @@
 
 // https://drafts.css-houdini.org/css-typed-om-1/#cssstylevalue
 // NOTE: should this be exposed to Window?
-[Pref="dom.worklet.enabled", Exposed=(Worklet)]
+[Pref="dom_worklet_enabled", Exposed=(Worklet)]
 interface CSSStyleValue {
     stringifier;
 };
diff --git a/components/script/dom/webidls/CanvasRenderingContext2D.webidl b/components/script/dom/webidls/CanvasRenderingContext2D.webidl
index 0a7dbf6ab94..4479d068186 100644
--- a/components/script/dom/webidls/CanvasRenderingContext2D.webidl
+++ b/components/script/dom/webidls/CanvasRenderingContext2D.webidl
@@ -139,12 +139,12 @@ interface mixin CanvasUserInterface {
 
 interface mixin CanvasText {
   // text (see also the CanvasPathDrawingStyles and CanvasTextDrawingStyles interfaces)
-  [Pref="dom.canvas_text.enabled"]
+  [Pref="dom_canvas_text_enabled"]
   undefined fillText(DOMString text, unrestricted double x, unrestricted double y,
                 optional unrestricted double maxWidth);
   //void strokeText(DOMString text, unrestricted double x, unrestricted double y,
   //                optional unrestricted double maxWidth);
-  [Pref="dom.canvas_text.enabled"]
+  [Pref="dom_canvas_text_enabled"]
   TextMetrics measureText(DOMString text);
 };
 
diff --git a/components/script/dom/webidls/Client.webidl b/components/script/dom/webidls/Client.webidl
index f5a9dee934e..f2b144ffa07 100644
--- a/components/script/dom/webidls/Client.webidl
+++ b/components/script/dom/webidls/Client.webidl
@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/ServiceWorker/#client
 
-[Pref="dom.serviceworker.enabled", Exposed=ServiceWorker]
+[Pref="dom_serviceworker_enabled", Exposed=ServiceWorker]
 interface Client {
   readonly attribute USVString url;
   readonly attribute FrameType frameType;
diff --git a/components/script/dom/webidls/CompositionEvent.webidl b/components/script/dom/webidls/CompositionEvent.webidl
index 1ed323d26b3..3eeba65e29a 100644
--- a/components/script/dom/webidls/CompositionEvent.webidl
+++ b/components/script/dom/webidls/CompositionEvent.webidl
@@ -8,7 +8,7 @@
  */
 
 // https://w3c.github.io/uievents/#idl-compositionevent
-[Exposed=Window, Pref="dom.composition_event.enabled"]
+[Exposed=Window, Pref="dom_composition_event_enabled"]
 interface CompositionEvent : UIEvent {
   [Throws] constructor(DOMString type, optional CompositionEventInit eventInitDict = {});
   readonly attribute DOMString data;
diff --git a/components/script/dom/webidls/Crypto.webidl b/components/script/dom/webidls/Crypto.webidl
index 828273f4afa..cdda53e27ac 100644
--- a/components/script/dom/webidls/Crypto.webidl
+++ b/components/script/dom/webidls/Crypto.webidl
@@ -13,7 +13,7 @@ partial interface mixin WindowOrWorkerGlobalScope {
 
 [Exposed=(Window,Worker)]
 interface Crypto {
-  [SecureContext, Pref="dom.crypto.subtle.enabled"] readonly attribute SubtleCrypto subtle;
+  [SecureContext, Pref="dom_crypto_subtle_enabled"] readonly attribute SubtleCrypto subtle;
   [Throws] ArrayBufferView getRandomValues(ArrayBufferView array);
   [SecureContext] DOMString randomUUID();
 };
diff --git a/components/script/dom/webidls/CryptoKey.webidl b/components/script/dom/webidls/CryptoKey.webidl
index 1cad0097df2..4387ef75d98 100644
--- a/components/script/dom/webidls/CryptoKey.webidl
+++ b/components/script/dom/webidls/CryptoKey.webidl
@@ -8,7 +8,7 @@ enum KeyType { "public", "private", "secret" };
 
 enum KeyUsage { "encrypt", "decrypt", "sign", "verify", "deriveKey", "deriveBits", "wrapKey", "unwrapKey" };
 
-[SecureContext, Exposed=(Window,Worker), Serializable, Pref="dom.crypto.subtle.enabled"]
+[SecureContext, Exposed=(Window,Worker), Serializable, Pref="dom_crypto_subtle_enabled"]
 interface CryptoKey {
   readonly attribute KeyType type;
   readonly attribute boolean extractable;
diff --git a/components/script/dom/webidls/CustomElementRegistry.webidl b/components/script/dom/webidls/CustomElementRegistry.webidl
index be3d19b1cdd..818e8892461 100644
--- a/components/script/dom/webidls/CustomElementRegistry.webidl
+++ b/components/script/dom/webidls/CustomElementRegistry.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://html.spec.whatwg.org/multipage/#customelementregistry
-[Exposed=Window, Pref="dom.custom_elements.enabled"]
+[Exposed=Window, Pref="dom_customelements_enabled"]
 interface CustomElementRegistry {
   [Throws, CEReactions]
   undefined define(
diff --git a/components/script/dom/webidls/Element.webidl b/components/script/dom/webidls/Element.webidl
index 1a99d5ec480..c7884925541 100644
--- a/components/script/dom/webidls/Element.webidl
+++ b/components/script/dom/webidls/Element.webidl
@@ -83,7 +83,7 @@ interface Element : Node {
   [CEReactions, Throws]
   undefined insertAdjacentHTML(DOMString position, DOMString html);
 
-  [Throws, Pref="dom.shadowdom.enabled"] ShadowRoot attachShadow(ShadowRootInit init);
+  [Throws, Pref="dom_shadowdom_enabled"] ShadowRoot attachShadow(ShadowRootInit init);
   readonly attribute ShadowRoot? shadowRoot;
 };
 
diff --git a/components/script/dom/webidls/ExtendableEvent.webidl b/components/script/dom/webidls/ExtendableEvent.webidl
index 0b030873fc5..cf8a42169a0 100644
--- a/components/script/dom/webidls/ExtendableEvent.webidl
+++ b/components/script/dom/webidls/ExtendableEvent.webidl
@@ -5,7 +5,7 @@
 // https://w3c.github.io/ServiceWorker/#extendable-event
 
 [Exposed=ServiceWorker,
- Pref="dom.serviceworker.enabled"]
+ Pref="dom_serviceworker_enabled"]
 interface ExtendableEvent : Event {
   [Throws] constructor(DOMString type,
  optional ExtendableEventInit eventInitDict = {});
diff --git a/components/script/dom/webidls/ExtendableMessageEvent.webidl b/components/script/dom/webidls/ExtendableMessageEvent.webidl
index 247c08e7989..66fbb46371e 100644
--- a/components/script/dom/webidls/ExtendableMessageEvent.webidl
+++ b/components/script/dom/webidls/ExtendableMessageEvent.webidl
@@ -5,7 +5,7 @@
 // https://w3c.github.io/ServiceWorker/#extendablemessage-event-section
 
 [Exposed=ServiceWorker,
- Pref="dom.serviceworker.enabled"]
+ Pref="dom_serviceworker_enabled"]
 interface ExtendableMessageEvent : ExtendableEvent {
   [Throws] constructor(DOMString type, optional ExtendableMessageEventInit eventInitDict = {});
   readonly attribute any data;
diff --git a/components/script/dom/webidls/FakeXRDevice.webidl b/components/script/dom/webidls/FakeXRDevice.webidl
index 22a2ddbbd27..dd0bb24b8a4 100644
--- a/components/script/dom/webidls/FakeXRDevice.webidl
+++ b/components/script/dom/webidls/FakeXRDevice.webidl
@@ -6,7 +6,7 @@
 
 // https://github.com/immersive-web/webxr-test-api/
 
-[Exposed=Window, Pref="dom.webxr.test"]
+[Exposed=Window, Pref="dom_webxr_test"]
 interface FakeXRDevice {
   // Sets the values to be used for subsequent requestAnimationFrame() callbacks.
   [Throws] undefined setViews(sequence<FakeXRViewInit> views, optional sequence<FakeXRViewInit> secondaryViews);
diff --git a/components/script/dom/webidls/FakeXRInputController.webidl b/components/script/dom/webidls/FakeXRInputController.webidl
index 42230c980bb..25237f54c7d 100644
--- a/components/script/dom/webidls/FakeXRInputController.webidl
+++ b/components/script/dom/webidls/FakeXRInputController.webidl
@@ -6,7 +6,7 @@
 
 // https://immersive-web.github.io/webxr-test-api/#fakexrinputcontroller
 
-[Exposed=Window, Pref="dom.webxr.test"]
+[Exposed=Window, Pref="dom_webxr_test"]
 interface FakeXRInputController {
   undefined setHandedness(XRHandedness handedness);
   undefined setTargetRayMode(XRTargetRayMode targetRayMode);
diff --git a/components/script/dom/webidls/GPUCanvasContext.webidl b/components/script/dom/webidls/GPUCanvasContext.webidl
index b85bb3c9bdf..e83421fa5ea 100644
--- a/components/script/dom/webidls/GPUCanvasContext.webidl
+++ b/components/script/dom/webidls/GPUCanvasContext.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://html.spec.whatwg.org/multipage/#htmlcanvaselement
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface GPUCanvasContext {
     readonly attribute (HTMLCanvasElement or OffscreenCanvas) canvas;
 };
diff --git a/components/script/dom/webidls/Gamepad.webidl b/components/script/dom/webidls/Gamepad.webidl
index d716f0c0bc4..bef601c5c7c 100644
--- a/components/script/dom/webidls/Gamepad.webidl
+++ b/components/script/dom/webidls/Gamepad.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://w3c.github.io/gamepad/#gamepad-interface
-[Exposed=Window, Pref="dom.gamepad.enabled"]
+[Exposed=Window, Pref="dom_gamepad_enabled"]
 interface Gamepad {
     readonly attribute DOMString id;
     readonly attribute long index;
diff --git a/components/script/dom/webidls/GamepadButton.webidl b/components/script/dom/webidls/GamepadButton.webidl
index 748d47232ac..d4aa41be8d9 100644
--- a/components/script/dom/webidls/GamepadButton.webidl
+++ b/components/script/dom/webidls/GamepadButton.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://w3c.github.io/gamepad/#gamepadbutton-interface
-[Exposed=Window, Pref="dom.gamepad.enabled"]
+[Exposed=Window, Pref="dom_gamepad_enabled"]
 interface GamepadButton {
     readonly attribute boolean pressed;
     readonly attribute boolean touched;
diff --git a/components/script/dom/webidls/GamepadButtonList.webidl b/components/script/dom/webidls/GamepadButtonList.webidl
index 34ea9857071..24a82a4b322 100644
--- a/components/script/dom/webidls/GamepadButtonList.webidl
+++ b/components/script/dom/webidls/GamepadButtonList.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://w3c.github.io/gamepad/#dom-gamepad-buttons
-[Exposed=Window, Pref="dom.gamepad.enabled"]
+[Exposed=Window, Pref="dom_gamepad_enabled"]
 interface GamepadButtonList {
   getter GamepadButton? item(unsigned long index);
   readonly attribute unsigned long length;
diff --git a/components/script/dom/webidls/GamepadEvent.webidl b/components/script/dom/webidls/GamepadEvent.webidl
index 0da800bafe2..0dc82e4083b 100644
--- a/components/script/dom/webidls/GamepadEvent.webidl
+++ b/components/script/dom/webidls/GamepadEvent.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://w3c.github.io/gamepad/#gamepadevent-interface
-[Exposed=Window, Pref="dom.gamepad.enabled"]
+[Exposed=Window, Pref="dom_gamepad_enabled"]
 interface GamepadEvent : Event {
   [Throws] constructor(DOMString type, GamepadEventInit eventInitDict);
   readonly attribute Gamepad gamepad;
diff --git a/components/script/dom/webidls/GamepadHapticActuator.webidl b/components/script/dom/webidls/GamepadHapticActuator.webidl
index 1961da4c541..db6f6eb5f8b 100644
--- a/components/script/dom/webidls/GamepadHapticActuator.webidl
+++ b/components/script/dom/webidls/GamepadHapticActuator.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://w3c.github.io/gamepad/#gamepadhapticactuator-interface
-[Exposed=Window, Pref="dom.gamepad.enabled"]
+[Exposed=Window, Pref="dom_gamepad_enabled"]
 interface GamepadHapticActuator {
   /* [SameObject] */ readonly attribute /* FrozenArray<GamepadHapticEffectType> */ any effects;
   [NewObject]
diff --git a/components/script/dom/webidls/GamepadPose.webidl b/components/script/dom/webidls/GamepadPose.webidl
index 5afa9f3251e..aeb5411b12b 100644
--- a/components/script/dom/webidls/GamepadPose.webidl
+++ b/components/script/dom/webidls/GamepadPose.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://w3c.github.io/gamepad/extensions.html#gamepadpose-interface
-[Exposed=Window, Pref="dom.gamepad.enabled"]
+[Exposed=Window, Pref="dom_gamepad_enabled"]
 interface GamepadPose {
   readonly attribute boolean hasOrientation;
   readonly attribute boolean hasPosition;
diff --git a/components/script/dom/webidls/HTMLCanvasElement.webidl b/components/script/dom/webidls/HTMLCanvasElement.webidl
index cbcb6b4d030..2e7be0389be 100644
--- a/components/script/dom/webidls/HTMLCanvasElement.webidl
+++ b/components/script/dom/webidls/HTMLCanvasElement.webidl
@@ -29,7 +29,7 @@ interface HTMLCanvasElement : HTMLElement {
 };
 
 partial interface HTMLCanvasElement {
-    [Pref="dom.canvas_capture.enabled"]
+    [Pref="dom_canvas_capture_enabled"]
     MediaStream captureStream (optional double frameRequestRate);
 };
 
diff --git a/components/script/dom/webidls/HTMLElement.webidl b/components/script/dom/webidls/HTMLElement.webidl
index a67a13d4be4..76bfada1b94 100644
--- a/components/script/dom/webidls/HTMLElement.webidl
+++ b/components/script/dom/webidls/HTMLElement.webidl
@@ -24,9 +24,9 @@ interface HTMLElement : Element {
   //         attribute DOMString itemId;
   //readonly attribute HTMLPropertiesCollection properties;
   //         attribute any itemValue; // acts as DOMString on setting
-  [Pref="dom.microdata.testing.enabled"]
+  [Pref="dom_microdata_testing_enabled"]
   sequence<DOMString>? propertyNames();
-  [Pref="dom.microdata.testing.enabled"]
+  [Pref="dom_microdata_testing_enabled"]
   sequence<DOMString>? itemtypes();
 
   // user interaction
diff --git a/components/script/dom/webidls/HTMLInputElement.webidl b/components/script/dom/webidls/HTMLInputElement.webidl
index 519198cebd9..724f2cff9b5 100644
--- a/components/script/dom/webidls/HTMLInputElement.webidl
+++ b/components/script/dom/webidls/HTMLInputElement.webidl
@@ -109,7 +109,7 @@ interface HTMLInputElement : HTMLElement {
   // also has obsolete members
 
   // Select with file-system paths for testing purpose
-  [Pref="dom.testing.htmlinputelement.select_files.enabled"]
+  [Pref="dom_testing_html_input_element_select_files_enabled"]
   undefined selectFiles(sequence<DOMString> path);
 };
 
diff --git a/components/script/dom/webidls/HTMLVideoElement.webidl b/components/script/dom/webidls/HTMLVideoElement.webidl
index d9e6b86e4bb..f4550e9857b 100644
--- a/components/script/dom/webidls/HTMLVideoElement.webidl
+++ b/components/script/dom/webidls/HTMLVideoElement.webidl
@@ -17,6 +17,6 @@ interface HTMLVideoElement : HTMLMediaElement {
 };
 
 partial interface HTMLVideoElement {
-  [Pref="media.testing.enabled"]
+  [Pref="media_testing_enabled"]
   attribute EventHandler onpostershown;
 };
diff --git a/components/script/dom/webidls/ImageBitmap.webidl b/components/script/dom/webidls/ImageBitmap.webidl
index e2ace645e74..aaa35c67995 100644
--- a/components/script/dom/webidls/ImageBitmap.webidl
+++ b/components/script/dom/webidls/ImageBitmap.webidl
@@ -10,7 +10,7 @@
  */
 
 //[Exposed=(Window,Worker), Serializable, Transferable]
-[Exposed=(Window,Worker), Pref="dom.imagebitmap.enabled"]
+[Exposed=(Window,Worker), Pref="dom_imagebitmap_enabled"]
 interface ImageBitmap {
   readonly attribute unsigned long width;
   readonly attribute unsigned long height;
diff --git a/components/script/dom/webidls/IntersectionObserver.webidl b/components/script/dom/webidls/IntersectionObserver.webidl
index dc24a856363..9607864408e 100644
--- a/components/script/dom/webidls/IntersectionObserver.webidl
+++ b/components/script/dom/webidls/IntersectionObserver.webidl
@@ -16,7 +16,7 @@ dictionary IntersectionObserverInit {
   boolean trackVisibility = false;
 };
 
-[Pref="dom.intersection_observer.enabled", Exposed=(Window)]
+[Pref="dom_intersection_observer_enabled", Exposed=(Window)]
 interface IntersectionObserver {
   constructor(IntersectionObserverCallback callback, optional IntersectionObserverInit options = {});
   readonly attribute (Element or Document)? root;
diff --git a/components/script/dom/webidls/IntersectionObserverEntry.webidl b/components/script/dom/webidls/IntersectionObserverEntry.webidl
index 108ad6636de..5e9423a965c 100644
--- a/components/script/dom/webidls/IntersectionObserverEntry.webidl
+++ b/components/script/dom/webidls/IntersectionObserverEntry.webidl
@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/IntersectionObserver/#intersection-observer-entry
 
-[Pref="dom.intersection_observer.enabled", Exposed=(Window)]
+[Pref="dom_intersection_observer_enabled", Exposed=(Window)]
 interface IntersectionObserverEntry {
   constructor(IntersectionObserverEntryInit intersectionObserverEntryInit);
   readonly attribute DOMHighResTimeStamp time;
diff --git a/components/script/dom/webidls/MediaDeviceInfo.webidl b/components/script/dom/webidls/MediaDeviceInfo.webidl
index ab24f8046f9..d6caaa43499 100644
--- a/components/script/dom/webidls/MediaDeviceInfo.webidl
+++ b/components/script/dom/webidls/MediaDeviceInfo.webidl
@@ -5,7 +5,7 @@
  // https://w3c.github.io/mediacapture-main/#device-info
 
 [Exposed=Window,
-SecureContext, Pref="dom.webrtc.enabled"]
+SecureContext, Pref="dom_webrtc_enabled"]
 interface MediaDeviceInfo {
   readonly attribute DOMString deviceId;
   readonly attribute MediaDeviceKind kind;
diff --git a/components/script/dom/webidls/MediaDevices.webidl b/components/script/dom/webidls/MediaDevices.webidl
index 53e6c3599a4..8d14e60abb5 100644
--- a/components/script/dom/webidls/MediaDevices.webidl
+++ b/components/script/dom/webidls/MediaDevices.webidl
@@ -5,7 +5,7 @@
 // https://w3c.github.io/mediacapture-main/#dom-mediadevices
 
 [Exposed=Window,
-SecureContext, Pref="dom.webrtc.enabled"]
+SecureContext, Pref="dom_webrtc_enabled"]
 interface MediaDevices : EventTarget {
     //                attribute EventHandler ondevicechange;
     Promise<sequence<MediaDeviceInfo>> enumerateDevices();
@@ -13,7 +13,7 @@ interface MediaDevices : EventTarget {
 
 partial interface Navigator {
     // [SameObject, SecureContext]
-    [Pref="dom.webrtc.enabled"] readonly        attribute MediaDevices mediaDevices;
+    [Pref="dom_webrtc_enabled"] readonly        attribute MediaDevices mediaDevices;
 };
 
 partial interface MediaDevices {
diff --git a/components/script/dom/webidls/MouseEvent.webidl b/components/script/dom/webidls/MouseEvent.webidl
index ba717f724a4..0a3c5c015fd 100644
--- a/components/script/dom/webidls/MouseEvent.webidl
+++ b/components/script/dom/webidls/MouseEvent.webidl
@@ -26,7 +26,7 @@ interface MouseEvent : UIEvent {
     readonly    attribute unsigned short buttons;
     //boolean getModifierState (DOMString keyArg);
 
-    [Pref="dom.mouseevent.which.enabled"]
+    [Pref="dom_mouse_event_which_enabled"]
     readonly    attribute long           which;
 };
 
diff --git a/components/script/dom/webidls/MutationObserver.webidl b/components/script/dom/webidls/MutationObserver.webidl
index baa9a1a79b0..4f643c7b222 100644
--- a/components/script/dom/webidls/MutationObserver.webidl
+++ b/components/script/dom/webidls/MutationObserver.webidl
@@ -7,7 +7,7 @@
  */
 
 // https://dom.spec.whatwg.org/#mutationobserver
-[Exposed=Window, Pref="dom.mutation_observer.enabled"]
+[Exposed=Window, Pref="dom_mutation_observer_enabled"]
 interface MutationObserver {
     [Throws] constructor(MutationCallback callback);
     [Throws]
diff --git a/components/script/dom/webidls/MutationRecord.webidl b/components/script/dom/webidls/MutationRecord.webidl
index 2c08fcea71f..edc5c9e8825 100644
--- a/components/script/dom/webidls/MutationRecord.webidl
+++ b/components/script/dom/webidls/MutationRecord.webidl
@@ -7,7 +7,7 @@
  */
 
 // https://dom.spec.whatwg.org/#mutationrecord
-[Pref="dom.mutation_observer.enabled", Exposed=Window]
+[Pref="dom_mutation_observer_enabled", Exposed=Window]
 interface MutationRecord {
     readonly attribute DOMString type;
     [SameObject]
diff --git a/components/script/dom/webidls/NavigationPreloadManager.webidl b/components/script/dom/webidls/NavigationPreloadManager.webidl
index 1c2e4d09189..026bcafea13 100644
--- a/components/script/dom/webidls/NavigationPreloadManager.webidl
+++ b/components/script/dom/webidls/NavigationPreloadManager.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://w3c.github.io/ServiceWorker/#navigation-preload-manager
-[Pref="dom.serviceworker.enabled", SecureContext, Exposed=(Window,Worker)]
+[Pref="dom_serviceworker_enabled", SecureContext, Exposed=(Window,Worker)]
 interface NavigationPreloadManager {
   Promise<undefined> enable();
   Promise<undefined> disable();
diff --git a/components/script/dom/webidls/Navigator.webidl b/components/script/dom/webidls/Navigator.webidl
index 2fcef010b4a..05fbdf62024 100644
--- a/components/script/dom/webidls/Navigator.webidl
+++ b/components/script/dom/webidls/Navigator.webidl
@@ -33,12 +33,12 @@ interface mixin NavigatorID {
 
 // https://webbluetoothcg.github.io/web-bluetooth/#navigator-extensions
 partial interface Navigator {
-  [SameObject, Pref="dom.bluetooth.enabled"] readonly attribute Bluetooth bluetooth;
+  [SameObject, Pref="dom_bluetooth_enabled"] readonly attribute Bluetooth bluetooth;
 };
 
 // https://w3c.github.io/ServiceWorker/#navigator-service-worker
 partial interface Navigator {
-  [SameObject, Pref="dom.serviceworker.enabled"] readonly attribute ServiceWorkerContainer serviceWorker;
+  [SameObject, Pref="dom_serviceworker_enabled"] readonly attribute ServiceWorkerContainer serviceWorker;
 };
 
 // https://html.spec.whatwg.org/multipage/#navigatorlanguage
@@ -63,12 +63,12 @@ interface mixin NavigatorCookies {
 // https://w3c.github.io/permissions/#navigator-and-workernavigator-extension
 [Exposed=(Window)]
 partial interface Navigator {
-  [Pref="dom.permissions.enabled"] readonly attribute Permissions permissions;
+  [Pref="dom_permissions_enabled"] readonly attribute Permissions permissions;
 };
 
 // https://w3c.github.io/gamepad/#navigator-interface-extension
 partial interface Navigator {
-  [Pref="dom.gamepad.enabled"] sequence<Gamepad?> getGamepads();
+  [Pref="dom_gamepad_enabled"] sequence<Gamepad?> getGamepads();
 };
 
 // https://html.spec.whatwg.org/multipage/#navigatorconcurrenthardware
diff --git a/components/script/dom/webidls/OffscreenCanvas.webidl b/components/script/dom/webidls/OffscreenCanvas.webidl
index 04c28f989a5..cc19cefa868 100644
--- a/components/script/dom/webidls/OffscreenCanvas.webidl
+++ b/components/script/dom/webidls/OffscreenCanvas.webidl
@@ -13,7 +13,7 @@ dictionary ImageEncodeOptions {
 
 //enum OffscreenRenderingContextId { "2d", "webgl", "webgl2" };
 
-[Exposed=(Window,Worker)/*, Transferable*/, Pref="dom.offscreen_canvas.enabled"]
+[Exposed=(Window,Worker)/*, Transferable*/, Pref="dom_offscreen_canvas_enabled"]
 interface OffscreenCanvas : EventTarget {
   [Throws] constructor([EnforceRange] unsigned long long width, [EnforceRange] unsigned long long height);
   attribute [EnforceRange] unsigned long long width;
diff --git a/components/script/dom/webidls/OffscreenCanvasRenderingContext2D.webidl b/components/script/dom/webidls/OffscreenCanvasRenderingContext2D.webidl
index c129bfa8e47..5d6aef5e014 100644
--- a/components/script/dom/webidls/OffscreenCanvasRenderingContext2D.webidl
+++ b/components/script/dom/webidls/OffscreenCanvasRenderingContext2D.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://html.spec.whatwg.org/multipage/#the-offscreen-2d-rendering-context
-[Exposed=(Window,Worker), Pref="dom.offscreen_canvas.enabled"]
+[Exposed=(Window,Worker), Pref="dom_offscreen_canvas_enabled"]
 interface OffscreenCanvasRenderingContext2D {
   //void commit();
   readonly attribute OffscreenCanvas canvas;
diff --git a/components/script/dom/webidls/PaintRenderingContext2D.webidl b/components/script/dom/webidls/PaintRenderingContext2D.webidl
index bc415450358..8361c298866 100644
--- a/components/script/dom/webidls/PaintRenderingContext2D.webidl
+++ b/components/script/dom/webidls/PaintRenderingContext2D.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://drafts.css-houdini.org/css-paint-api/#paintrenderingcontext2d
-[Pref="dom.worklet.enabled", Exposed=PaintWorklet]
+[Pref="dom_worklet_enabled", Exposed=PaintWorklet]
 interface PaintRenderingContext2D {
 };
 PaintRenderingContext2D includes CanvasState;
diff --git a/components/script/dom/webidls/PaintSize.webidl b/components/script/dom/webidls/PaintSize.webidl
index ed1b46d29f4..2c3e669d32e 100644
--- a/components/script/dom/webidls/PaintSize.webidl
+++ b/components/script/dom/webidls/PaintSize.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://drafts.css-houdini.org/css-paint-api/#paintsize
-[Pref="dom.worklet.enabled", Exposed=PaintWorklet]
+[Pref="dom_worklet_enabled", Exposed=PaintWorklet]
 interface PaintSize {
     readonly attribute double width;
     readonly attribute double height;
diff --git a/components/script/dom/webidls/PaintWorkletGlobalScope.webidl b/components/script/dom/webidls/PaintWorkletGlobalScope.webidl
index 981df09321f..a5918c06616 100644
--- a/components/script/dom/webidls/PaintWorkletGlobalScope.webidl
+++ b/components/script/dom/webidls/PaintWorkletGlobalScope.webidl
@@ -3,11 +3,11 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://drafts.css-houdini.org/css-paint-api/#paintworkletglobalscope
-[Global=(Worklet,PaintWorklet), Pref="dom.worklet.enabled", Exposed=PaintWorklet]
+[Global=(Worklet,PaintWorklet), Pref="dom_worklet_enabled", Exposed=PaintWorklet]
 interface PaintWorkletGlobalScope : WorkletGlobalScope {
     [Throws] undefined registerPaint(DOMString name, VoidFunction paintCtor);
     // This function is to be used only for testing, and should not be
     // accessible outside of that use.
-    [Pref="dom.worklet.blockingsleep.enabled"]
+    [Pref="dom_worklet_blockingsleep_enabled"]
     undefined sleep(unsigned long long ms);
 };
diff --git a/components/script/dom/webidls/PerformanceNavigationTiming.webidl b/components/script/dom/webidls/PerformanceNavigationTiming.webidl
index 8bd657dbdfb..4757e7fd7d0 100644
--- a/components/script/dom/webidls/PerformanceNavigationTiming.webidl
+++ b/components/script/dom/webidls/PerformanceNavigationTiming.webidl
@@ -27,6 +27,6 @@ interface PerformanceNavigationTiming : PerformanceResourceTiming {
     readonly attribute unsigned short       redirectCount;
     [Default] object toJSON();
     /* Servo-only attribute for measuring when the top-level document (not iframes) is complete. */
-    [Pref="dom.testperf.enabled"]
+    [Pref="dom_testperf_enabled"]
     readonly attribute DOMHighResTimeStamp  topLevelDomComplete;
 };
diff --git a/components/script/dom/webidls/PermissionStatus.webidl b/components/script/dom/webidls/PermissionStatus.webidl
index 83c0371e0de..a5aebda20dd 100644
--- a/components/script/dom/webidls/PermissionStatus.webidl
+++ b/components/script/dom/webidls/PermissionStatus.webidl
@@ -28,7 +28,7 @@ enum PermissionName {
   "persistent-storage",
 };
 
-[Pref="dom.permissions.enabled", Exposed=(Window,Worker)]
+[Pref="dom_permissions_enabled", Exposed=(Window,Worker)]
 interface PermissionStatus : EventTarget {
   readonly attribute PermissionState state;
   attribute EventHandler onchange;
diff --git a/components/script/dom/webidls/Permissions.webidl b/components/script/dom/webidls/Permissions.webidl
index 5b4092cc645..21e20eb2bf5 100644
--- a/components/script/dom/webidls/Permissions.webidl
+++ b/components/script/dom/webidls/Permissions.webidl
@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/permissions/#permissions-interface
 
-[Pref="dom.permissions.enabled", Exposed=(Window,Worker)]
+[Pref="dom_permissions_enabled", Exposed=(Window,Worker)]
 interface Permissions {
   Promise<PermissionStatus> query(object permissionDesc);
 
diff --git a/components/script/dom/webidls/RTCDataChannel.webidl b/components/script/dom/webidls/RTCDataChannel.webidl
index e67c299bcea..419b05bd3f9 100644
--- a/components/script/dom/webidls/RTCDataChannel.webidl
+++ b/components/script/dom/webidls/RTCDataChannel.webidl
@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/webrtc-pc/#dom-rtcdatachannel
 
-[Exposed=Window, Pref="dom.webrtc.enabled"]
+[Exposed=Window, Pref="dom_webrtc_enabled"]
 interface RTCDataChannel : EventTarget {
   readonly attribute USVString label;
   readonly attribute boolean ordered;
diff --git a/components/script/dom/webidls/RTCDataChannelEvent.webidl b/components/script/dom/webidls/RTCDataChannelEvent.webidl
index bc564a12138..5d2a8e6df24 100644
--- a/components/script/dom/webidls/RTCDataChannelEvent.webidl
+++ b/components/script/dom/webidls/RTCDataChannelEvent.webidl
@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/webrtc-pc/#dom-rtcdatachannelevent
 
-[Exposed=Window, Pref="dom.webrtc.enabled"]
+[Exposed=Window, Pref="dom_webrtc_enabled"]
 interface RTCDataChannelEvent : Event {
   constructor(DOMString type, RTCDataChannelEventInit eventInitDict);
   readonly attribute RTCDataChannel channel;
diff --git a/components/script/dom/webidls/RTCError.webidl b/components/script/dom/webidls/RTCError.webidl
index f7ffa3d2d57..a745cf5e77f 100644
--- a/components/script/dom/webidls/RTCError.webidl
+++ b/components/script/dom/webidls/RTCError.webidl
@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/webrtc-pc/#dom-rtcerror
 
-[Exposed=Window, Pref="dom.webrtc.enabled"]
+[Exposed=Window, Pref="dom_webrtc_enabled"]
 interface RTCError : DOMException {
   constructor(RTCErrorInit init, optional DOMString message = "");
   readonly attribute RTCErrorDetailType errorDetail;
diff --git a/components/script/dom/webidls/RTCErrorEvent.webidl b/components/script/dom/webidls/RTCErrorEvent.webidl
index d3ac256744c..c5b7c3e9cc8 100644
--- a/components/script/dom/webidls/RTCErrorEvent.webidl
+++ b/components/script/dom/webidls/RTCErrorEvent.webidl
@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/webrtc-pc/#dom-rtcerrorevent
 
-[Exposed=Window, Pref="dom.webrtc.enabled"]
+[Exposed=Window, Pref="dom_webrtc_enabled"]
 interface RTCErrorEvent : Event {
   constructor(DOMString type, RTCErrorEventInit eventInitDict);
   [SameObject] readonly attribute RTCError error;
diff --git a/components/script/dom/webidls/RTCIceCandidate.webidl b/components/script/dom/webidls/RTCIceCandidate.webidl
index fde0421c8c0..266fe353f37 100644
--- a/components/script/dom/webidls/RTCIceCandidate.webidl
+++ b/components/script/dom/webidls/RTCIceCandidate.webidl
@@ -5,7 +5,7 @@
 // https://w3c.github.io/webrtc-pc/#rtcicecandidate-interface
 
 
-[Exposed=Window, Pref="dom.webrtc.enabled"]
+[Exposed=Window, Pref="dom_webrtc_enabled"]
 interface RTCIceCandidate {
     [Throws] constructor(optional RTCIceCandidateInit candidateInitDict = {});
     readonly attribute DOMString               candidate;
diff --git a/components/script/dom/webidls/RTCPeerConnection.webidl b/components/script/dom/webidls/RTCPeerConnection.webidl
index 85a7297fce1..24ced7bcce6 100644
--- a/components/script/dom/webidls/RTCPeerConnection.webidl
+++ b/components/script/dom/webidls/RTCPeerConnection.webidl
@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/webrtc-pc/#interface-definition
 
-[Exposed=Window, Pref="dom.webrtc.enabled"]
+[Exposed=Window, Pref="dom_webrtc_enabled"]
 interface RTCPeerConnection : EventTarget {
     [Throws] constructor(optional RTCConfiguration configuration = {});
     Promise<RTCSessionDescriptionInit> createOffer(optional RTCOfferOptions options = {});
@@ -138,7 +138,7 @@ partial interface RTCPeerConnection {
     // RTCRtpSender                addTrack(MediaStreamTrack track,
     //                                      MediaStream... streams);
     // void                        removeTrack(RTCRtpSender sender);
-    [Pref="dom.webrtc.transceiver.enabled"]
+    [Pref="dom_webrtc_transceiver_enabled"]
     RTCRtpTransceiver           addTransceiver((MediaStreamTrack or DOMString) trackOrKind,
                                                optional RTCRtpTransceiverInit init = {});
     attribute EventHandler ontrack;
diff --git a/components/script/dom/webidls/RTCPeerConnectionIceEvent.webidl b/components/script/dom/webidls/RTCPeerConnectionIceEvent.webidl
index 2ffd69cea50..95094c45f3b 100644
--- a/components/script/dom/webidls/RTCPeerConnectionIceEvent.webidl
+++ b/components/script/dom/webidls/RTCPeerConnectionIceEvent.webidl
@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/webrtc-pc/#rtcpeerconnectioniceevent
 
-[Exposed=Window, Pref="dom.webrtc.enabled"]
+[Exposed=Window, Pref="dom_webrtc_enabled"]
 interface RTCPeerConnectionIceEvent : Event {
     [Throws] constructor(DOMString type, optional RTCPeerConnectionIceEventInit eventInitDict = {});
     readonly attribute RTCIceCandidate? candidate;
diff --git a/components/script/dom/webidls/RTCRtpSender.webidl b/components/script/dom/webidls/RTCRtpSender.webidl
index 752ab7682b8..938ca9e8a63 100644
--- a/components/script/dom/webidls/RTCRtpSender.webidl
+++ b/components/script/dom/webidls/RTCRtpSender.webidl
@@ -34,7 +34,7 @@ dictionary RTCRtpSendParameters : RTCRtpParameters {
   required sequence<RTCRtpEncodingParameters> encodings;
 };
 
-[Exposed=Window, Pref="dom.webrtc.transceiver.enabled"]
+[Exposed=Window, Pref="dom_webrtc_transceiver_enabled"]
 interface RTCRtpSender {
   //readonly attribute MediaStreamTrack? track;
   //readonly attribute RTCDtlsTransport? transport;
diff --git a/components/script/dom/webidls/RTCRtpTransceiver.webidl b/components/script/dom/webidls/RTCRtpTransceiver.webidl
index 408c2708709..f11b9853682 100644
--- a/components/script/dom/webidls/RTCRtpTransceiver.webidl
+++ b/components/script/dom/webidls/RTCRtpTransceiver.webidl
@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/webrtc-pc/#rtcrtptransceiver-interface
 
-[Exposed=Window, Pref="dom.webrtc.transceiver.enabled"]
+[Exposed=Window, Pref="dom_webrtc_transceiver_enabled"]
 interface RTCRtpTransceiver {
   //readonly attribute DOMString? mid;
   [SameObject] readonly attribute RTCRtpSender sender;
diff --git a/components/script/dom/webidls/RTCSessionDescription.webidl b/components/script/dom/webidls/RTCSessionDescription.webidl
index f13d0fd0d9f..0fb325eae41 100644
--- a/components/script/dom/webidls/RTCSessionDescription.webidl
+++ b/components/script/dom/webidls/RTCSessionDescription.webidl
@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/webrtc-pc/#rtcsessiondescription-class
 
-[Exposed=Window, Pref="dom.webrtc.enabled"]
+[Exposed=Window, Pref="dom_webrtc_enabled"]
 interface RTCSessionDescription {
     [Throws] constructor(RTCSessionDescriptionInit descriptionInitDict);
     readonly attribute RTCSdpType type;
diff --git a/components/script/dom/webidls/RTCTrackEvent.webidl b/components/script/dom/webidls/RTCTrackEvent.webidl
index c2283e5a803..c43b86710b4 100644
--- a/components/script/dom/webidls/RTCTrackEvent.webidl
+++ b/components/script/dom/webidls/RTCTrackEvent.webidl
@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/webrtc-pc/#dom-rtctrackevent
 
-[Exposed=Window, Pref="dom.webrtc.enabled"]
+[Exposed=Window, Pref="dom_webrtc_enabled"]
 interface RTCTrackEvent : Event {
     [Throws] constructor(DOMString type, RTCTrackEventInit eventInitDict);
     // readonly attribute RTCRtpReceiver           receiver;
diff --git a/components/script/dom/webidls/ResizeObserver.webidl b/components/script/dom/webidls/ResizeObserver.webidl
index fc0a87589d5..2f3b9064477 100644
--- a/components/script/dom/webidls/ResizeObserver.webidl
+++ b/components/script/dom/webidls/ResizeObserver.webidl
@@ -4,7 +4,7 @@
 
 // https://drafts.csswg.org/resize-observer/#resize-observer-interface
 
-[Pref="dom.resize_observer.enabled", Exposed=(Window)]
+[Pref="dom_resize_observer_enabled", Exposed=(Window)]
 interface ResizeObserver {
     constructor(ResizeObserverCallback callback);
     undefined observe(Element target, optional ResizeObserverOptions options = {});
diff --git a/components/script/dom/webidls/ResizeObserverEntry.webidl b/components/script/dom/webidls/ResizeObserverEntry.webidl
index 8cb8802023a..0b7b5c2f5a9 100644
--- a/components/script/dom/webidls/ResizeObserverEntry.webidl
+++ b/components/script/dom/webidls/ResizeObserverEntry.webidl
@@ -4,7 +4,7 @@
 
  // https://drafts.csswg.org/resize-observer/#resize-observer-entry-interface
 
-[Pref="dom.resize_observer.enabled", Exposed=Window]
+[Pref="dom_resize_observer_enabled", Exposed=Window]
 interface ResizeObserverEntry {
     readonly attribute Element target;
     readonly attribute DOMRectReadOnly contentRect;
diff --git a/components/script/dom/webidls/ResizeObserverSize.webidl b/components/script/dom/webidls/ResizeObserverSize.webidl
index 5cc8db2dbcd..e4bcb1ace78 100644
--- a/components/script/dom/webidls/ResizeObserverSize.webidl
+++ b/components/script/dom/webidls/ResizeObserverSize.webidl
@@ -4,7 +4,7 @@
 
 // https://drafts.csswg.org/resize-observer/#resizeobserversize
 
-[Pref="dom.resize_observer.enabled", Exposed=Window]
+[Pref="dom_resize_observer_enabled", Exposed=Window]
 interface ResizeObserverSize {
     readonly attribute unrestricted double inlineSize;
     readonly attribute unrestricted double blockSize;
diff --git a/components/script/dom/webidls/SVGElement.webidl b/components/script/dom/webidls/SVGElement.webidl
index e826c741e66..e6bc468d5dc 100644
--- a/components/script/dom/webidls/SVGElement.webidl
+++ b/components/script/dom/webidls/SVGElement.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://svgwg.org/svg2-draft/types.html#InterfaceSVGElement
-[Exposed=Window, Pref="dom.svg.enabled"]
+[Exposed=Window, Pref="dom_svg_enabled"]
 interface SVGElement : Element {
 
   //[SameObject] readonly attribute SVGAnimatedString className;
diff --git a/components/script/dom/webidls/SVGGraphicsElement.webidl b/components/script/dom/webidls/SVGGraphicsElement.webidl
index 052182e374d..ab08503e7ef 100644
--- a/components/script/dom/webidls/SVGGraphicsElement.webidl
+++ b/components/script/dom/webidls/SVGGraphicsElement.webidl
@@ -10,7 +10,7 @@
 //  boolean clipped = false;
 //};
 
-[Exposed=Window, Abstract, Pref="dom.svg.enabled"]
+[Exposed=Window, Abstract, Pref="dom_svg_enabled"]
 interface SVGGraphicsElement : SVGElement {
   //[SameObject] readonly attribute SVGAnimatedTransformList transform;
 
diff --git a/components/script/dom/webidls/SVGSVGElement.webidl b/components/script/dom/webidls/SVGSVGElement.webidl
index 0e61776a40e..25b390cf15a 100644
--- a/components/script/dom/webidls/SVGSVGElement.webidl
+++ b/components/script/dom/webidls/SVGSVGElement.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://svgwg.org/svg2-draft/struct.html#InterfaceSVGSVGElement
-[Exposed=Window, Pref="dom.svg.enabled"]
+[Exposed=Window, Pref="dom_svg_enabled"]
 interface SVGSVGElement : SVGGraphicsElement {
 
   //[SameObject] readonly attribute SVGAnimatedLength x;
diff --git a/components/script/dom/webidls/ServiceWorker.webidl b/components/script/dom/webidls/ServiceWorker.webidl
index a5bc8938602..ee12c92b6e2 100644
--- a/components/script/dom/webidls/ServiceWorker.webidl
+++ b/components/script/dom/webidls/ServiceWorker.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://w3c.github.io/ServiceWorker/#serviceworker-interface
-[Pref="dom.serviceworker.enabled", SecureContext, Exposed=(Window,Worker)]
+[Pref="dom_serviceworker_enabled", SecureContext, Exposed=(Window,Worker)]
 interface ServiceWorker : EventTarget {
   readonly attribute USVString scriptURL;
   readonly attribute ServiceWorkerState state;
diff --git a/components/script/dom/webidls/ServiceWorkerContainer.webidl b/components/script/dom/webidls/ServiceWorkerContainer.webidl
index 18deb5e58f4..540079583b9 100644
--- a/components/script/dom/webidls/ServiceWorkerContainer.webidl
+++ b/components/script/dom/webidls/ServiceWorkerContainer.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://w3c.github.io/ServiceWorker/#serviceworkercontainer-interface
-[Pref="dom.serviceworker.enabled", Exposed=(Window,Worker)]
+[Pref="dom_serviceworker_enabled", Exposed=(Window,Worker)]
 interface ServiceWorkerContainer : EventTarget {
   readonly attribute ServiceWorker? controller;
   //readonly attribute Promise<ServiceWorkerRegistration> ready;
diff --git a/components/script/dom/webidls/ServiceWorkerGlobalScope.webidl b/components/script/dom/webidls/ServiceWorkerGlobalScope.webidl
index 257f3ff3252..f7535867deb 100644
--- a/components/script/dom/webidls/ServiceWorkerGlobalScope.webidl
+++ b/components/script/dom/webidls/ServiceWorkerGlobalScope.webidl
@@ -5,7 +5,7 @@
 // https://w3c.github.io/ServiceWorker/#serviceworkerglobalscope
 
 [Global=(Worker,ServiceWorker), Exposed=ServiceWorker,
- Pref="dom.serviceworker.enabled"]
+ Pref="dom_serviceworker_enabled"]
 interface ServiceWorkerGlobalScope : WorkerGlobalScope {
   // A container for a list of Client objects that correspond to
   // browsing contexts (or shared workers) that are on the origin of this SW
diff --git a/components/script/dom/webidls/ServiceWorkerRegistration.webidl b/components/script/dom/webidls/ServiceWorkerRegistration.webidl
index f7a10659513..29982ee8ec3 100644
--- a/components/script/dom/webidls/ServiceWorkerRegistration.webidl
+++ b/components/script/dom/webidls/ServiceWorkerRegistration.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://w3c.github.io/ServiceWorker/#serviceworkerregistration-interface
-[Pref="dom.serviceworker.enabled", SecureContext, Exposed=(Window,Worker)]
+[Pref="dom_serviceworker_enabled", SecureContext, Exposed=(Window,Worker)]
 interface ServiceWorkerRegistration : EventTarget {
   readonly attribute ServiceWorker? installing;
   readonly attribute ServiceWorker? waiting;
diff --git a/components/script/dom/webidls/StylePropertyMapReadOnly.webidl b/components/script/dom/webidls/StylePropertyMapReadOnly.webidl
index 7f3860ee701..b427ebd7ba0 100644
--- a/components/script/dom/webidls/StylePropertyMapReadOnly.webidl
+++ b/components/script/dom/webidls/StylePropertyMapReadOnly.webidl
@@ -4,7 +4,7 @@
 
 // https://drafts.css-houdini.org/css-typed-om-1/#stylepropertymapreadonly
 // NOTE: should this be exposed to Window?
-[Pref="dom.worklet.enabled", Exposed=(Worklet)]
+[Pref="dom_worklet_enabled", Exposed=(Worklet)]
 interface StylePropertyMapReadOnly {
     CSSStyleValue? get(DOMString property);
     // sequence<CSSStyleValue> getAll(DOMString property);
diff --git a/components/script/dom/webidls/SubtleCrypto.webidl b/components/script/dom/webidls/SubtleCrypto.webidl
index be01cebf589..e0bc1bc04a5 100644
--- a/components/script/dom/webidls/SubtleCrypto.webidl
+++ b/components/script/dom/webidls/SubtleCrypto.webidl
@@ -18,7 +18,7 @@ dictionary KeyAlgorithm {
 
 enum KeyFormat { "raw", "spki", "pkcs8", "jwk" };
 
-[SecureContext,Exposed=(Window,Worker),Pref="dom.crypto.subtle.enabled"]
+[SecureContext,Exposed=(Window,Worker),Pref="dom_crypto_subtle_enabled"]
 interface SubtleCrypto {
   Promise<any> encrypt(AlgorithmIdentifier algorithm,
                        CryptoKey key,
diff --git a/components/script/dom/webidls/TestBinding.webidl b/components/script/dom/webidls/TestBinding.webidl
index bd6cb2432a4..ee13ed57d55 100644
--- a/components/script/dom/webidls/TestBinding.webidl
+++ b/components/script/dom/webidls/TestBinding.webidl
@@ -100,7 +100,7 @@ dictionary TestURLLike {
   required DOMString href;
 };
 
-[Pref="dom.testbinding.enabled",
+[Pref="dom_testbinding_enabled",
  Exposed=(Window,Worker)
 ]
 interface TestBinding {
@@ -516,28 +516,28 @@ interface TestBinding {
   boolean BooleanMozPreference(DOMString pref_name);
   DOMString StringMozPreference(DOMString pref_name);
 
-  [Pref="dom.testbinding.prefcontrolled.enabled"]
+  [Pref="dom_testbinding_prefcontrolled_enabled"]
   readonly attribute boolean prefControlledAttributeDisabled;
-  [Pref="dom.testbinding.prefcontrolled.enabled"]
+  [Pref="dom_testbinding_prefcontrolled_enabled"]
   static readonly attribute boolean prefControlledStaticAttributeDisabled;
-  [Pref="dom.testbinding.prefcontrolled.enabled"]
+  [Pref="dom_testbinding_prefcontrolled_enabled"]
   undefined prefControlledMethodDisabled();
-  [Pref="dom.testbinding.prefcontrolled.enabled"]
+  [Pref="dom_testbinding_prefcontrolled_enabled"]
   static undefined prefControlledStaticMethodDisabled();
-  [Pref="dom.testbinding.prefcontrolled.enabled"]
+  [Pref="dom_testbinding_prefcontrolled_enabled"]
   const unsigned short prefControlledConstDisabled = 0;
-  [Pref="layout.animations.test.enabled"]
+  [Pref="layout_animations_test_enabled"]
   undefined advanceClock(long millis);
 
-  [Pref="dom.testbinding.prefcontrolled2.enabled"]
+  [Pref="dom_testbinding_prefcontrolled2_enabled"]
   readonly attribute boolean prefControlledAttributeEnabled;
-  [Pref="dom.testbinding.prefcontrolled2.enabled"]
+  [Pref="dom_testbinding_prefcontrolled2_enabled"]
   static readonly attribute boolean prefControlledStaticAttributeEnabled;
-  [Pref="dom.testbinding.prefcontrolled2.enabled"]
+  [Pref="dom_testbinding_prefcontrolled2_enabled"]
   undefined prefControlledMethodEnabled();
-  [Pref="dom.testbinding.prefcontrolled2.enabled"]
+  [Pref="dom_testbinding_prefcontrolled2_enabled"]
   static undefined prefControlledStaticMethodEnabled();
-  [Pref="dom.testbinding.prefcontrolled2.enabled"]
+  [Pref="dom_testbinding_prefcontrolled2_enabled"]
   const unsigned short prefControlledConstEnabled = 0;
 
   [Func="TestBinding::condition_unsatisfied"]
@@ -609,11 +609,11 @@ callback SimpleCallback = undefined(any value);
 callback callbackWithOnlyOneOptionalArg = Promise<undefined> (optional any reason);
 
 partial interface TestBinding {
-  [Pref="dom.testable_crash.enabled"]
+  [Pref="dom_testable_crash_enabled"]
   undefined crashHard();
 };
 
-[Exposed=(Window,Worker), Pref="dom.testbinding.enabled"]
+[Exposed=(Window,Worker), Pref="dom_testbinding_enabled"]
 namespace TestNS {
     const unsigned long ONE   = 1;
     const unsigned long TWO   = 0x2;
diff --git a/components/script/dom/webidls/TestBindingIterable.webidl b/components/script/dom/webidls/TestBindingIterable.webidl
index 46a2d319e3d..cc7628af707 100644
--- a/components/script/dom/webidls/TestBindingIterable.webidl
+++ b/components/script/dom/webidls/TestBindingIterable.webidl
@@ -5,7 +5,7 @@
 // This interface is entirely internal to Servo, and should not be accessible to
 // web pages.
 
-[Pref="dom.testbinding.enabled", Exposed=(Window,Worker)]
+[Pref="dom_testbinding_enabled", Exposed=(Window,Worker)]
 interface TestBindingIterable {
   [Throws] constructor();
   undefined add(DOMString arg);
diff --git a/components/script/dom/webidls/TestBindingMaplike.webidl b/components/script/dom/webidls/TestBindingMaplike.webidl
index f9712d63a8a..8debb804a3e 100644
--- a/components/script/dom/webidls/TestBindingMaplike.webidl
+++ b/components/script/dom/webidls/TestBindingMaplike.webidl
@@ -5,7 +5,7 @@
 // This interface is entirely internal to Servo, and should not be accessible to
 // web pages.
 
-[Pref="dom.testbinding.enabled", Exposed=(Window,Worker)]
+[Pref="dom_testbinding_enabled", Exposed=(Window,Worker)]
 interface TestBindingMaplike {
   [Throws]
   constructor();
diff --git a/components/script/dom/webidls/TestBindingPairIterable.webidl b/components/script/dom/webidls/TestBindingPairIterable.webidl
index 64499e7464c..e3106949e3e 100644
--- a/components/script/dom/webidls/TestBindingPairIterable.webidl
+++ b/components/script/dom/webidls/TestBindingPairIterable.webidl
@@ -5,7 +5,7 @@
 // This interface is entirely internal to Servo, and should not be accessible to
 // web pages.
 
-[Pref="dom.testbinding.enabled", Exposed=(Window,Worker)]
+[Pref="dom_testbinding_enabled", Exposed=(Window,Worker)]
 interface TestBindingPairIterable {
   [Throws] constructor();
   undefined add(DOMString key, unsigned long value);
diff --git a/components/script/dom/webidls/TestBindingProxy.webidl b/components/script/dom/webidls/TestBindingProxy.webidl
index b16d5104242..957db0f0302 100644
--- a/components/script/dom/webidls/TestBindingProxy.webidl
+++ b/components/script/dom/webidls/TestBindingProxy.webidl
@@ -11,7 +11,7 @@
 // This interface is entirely internal to Servo, and should not be accessible to
 // web pages.
 
-[Pref="dom.testbinding.enabled", Exposed=(Window,Worker)]
+[Pref="dom_testbinding_enabled", Exposed=(Window,Worker)]
 interface TestBindingProxy : TestBinding {
   readonly attribute unsigned long length;
 
diff --git a/components/script/dom/webidls/TestBindingSetlike.webidl b/components/script/dom/webidls/TestBindingSetlike.webidl
index c8cfcf73b86..16b264bb9f6 100644
--- a/components/script/dom/webidls/TestBindingSetlike.webidl
+++ b/components/script/dom/webidls/TestBindingSetlike.webidl
@@ -5,7 +5,7 @@
 // This interface is entirely internal to Servo, and should not be accessible to
 // web pages.
 
-[Pref="dom.testbinding.enabled", Exposed=(Window,Worker)]
+[Pref="dom_testbinding_enabled", Exposed=(Window,Worker)]
 interface TestBindingSetlike {
   [Throws]
   constructor();
diff --git a/components/script/dom/webidls/TestRunner.webidl b/components/script/dom/webidls/TestRunner.webidl
index 448be17c4d4..4be17153247 100644
--- a/components/script/dom/webidls/TestRunner.webidl
+++ b/components/script/dom/webidls/TestRunner.webidl
@@ -6,7 +6,7 @@
 
 // callback BluetoothManualChooserEventsCallback = void(sequence<DOMString> events);
 
-[Pref="dom.bluetooth.testing.enabled", Exposed=Window]
+[Pref="dom_bluetooth_testing_enabled", Exposed=Window]
 interface TestRunner {
   [Throws]
   undefined setBluetoothMockDataSet(DOMString dataSetName);
diff --git a/components/script/dom/webidls/TestWorklet.webidl b/components/script/dom/webidls/TestWorklet.webidl
index 81b02da0731..8e5898736b0 100644
--- a/components/script/dom/webidls/TestWorklet.webidl
+++ b/components/script/dom/webidls/TestWorklet.webidl
@@ -5,7 +5,7 @@
 // This interface is entirely internal to Servo, and should not be accessible to
 // web pages.
 
-[Pref="dom.worklet.testing.enabled", Exposed=(Window)]
+[Pref="dom_worklet_testing_enabled", Exposed=(Window)]
 interface TestWorklet {
    [Throws] constructor();
    [NewObject] Promise<undefined> addModule(USVString moduleURL, optional WorkletOptions options = {});
diff --git a/components/script/dom/webidls/TestWorkletGlobalScope.webidl b/components/script/dom/webidls/TestWorkletGlobalScope.webidl
index 1c2735dbc65..86599a2c257 100644
--- a/components/script/dom/webidls/TestWorkletGlobalScope.webidl
+++ b/components/script/dom/webidls/TestWorkletGlobalScope.webidl
@@ -5,7 +5,7 @@
 // This interface is entirely internal to Servo, and should not be accessible to
 // web pages.
 
-[Global=(Worklet,TestWorklet), Pref="dom.worklet.enabled", Exposed=TestWorklet]
+[Global=(Worklet,TestWorklet), Pref="dom_worklet_enabled", Exposed=TestWorklet]
 interface TestWorkletGlobalScope : WorkletGlobalScope {
     undefined registerKeyValue(DOMString key, DOMString value);
 };
diff --git a/components/script/dom/webidls/TextMetrics.webidl b/components/script/dom/webidls/TextMetrics.webidl
index efba27450fe..ebf0bd8a3dc 100644
--- a/components/script/dom/webidls/TextMetrics.webidl
+++ b/components/script/dom/webidls/TextMetrics.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://html.spec.whatwg.org/multipage/#textmetrics
-[Exposed=(PaintWorklet, Window, Worker), Pref="dom.canvas_text.enabled"]
+[Exposed=(PaintWorklet, Window, Worker), Pref="dom_canvas_text_enabled"]
 interface TextMetrics {
   // x-direction
   readonly attribute double width; // advance width
diff --git a/components/script/dom/webidls/VTTCue.webidl b/components/script/dom/webidls/VTTCue.webidl
index 073aa12f79b..ccbd342a788 100644
--- a/components/script/dom/webidls/VTTCue.webidl
+++ b/components/script/dom/webidls/VTTCue.webidl
@@ -11,7 +11,7 @@ enum LineAlignSetting { "start", "center", "end" };
 enum PositionAlignSetting { "line-left", "center", "line-right", "auto" };
 enum AlignSetting { "start", "center", "end", "left", "right" };
 
-[Pref="dom.webvtt.enabled", Exposed=Window]
+[Pref="dom_webvtt_enabled", Exposed=Window]
 interface VTTCue : TextTrackCue {
   constructor(double startTime, double endTime, DOMString text);
   attribute VTTRegion? region;
diff --git a/components/script/dom/webidls/VTTRegion.webidl b/components/script/dom/webidls/VTTRegion.webidl
index 12fbe16170b..f4a616ef323 100644
--- a/components/script/dom/webidls/VTTRegion.webidl
+++ b/components/script/dom/webidls/VTTRegion.webidl
@@ -6,7 +6,7 @@
 
 enum ScrollSetting { "" /* none */, "up"};
 
-[Pref="dom.webvtt.enabled", Exposed=Window]
+[Pref="dom_webvtt_enabled", Exposed=Window]
 interface VTTRegion {
   [Throws] constructor();
   attribute DOMString id;
diff --git a/components/script/dom/webidls/WebGLQuery.webidl b/components/script/dom/webidls/WebGLQuery.webidl
index 04b3711dd86..feea145c611 100644
--- a/components/script/dom/webidls/WebGLQuery.webidl
+++ b/components/script/dom/webidls/WebGLQuery.webidl
@@ -6,6 +6,6 @@
 // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.8
 //
 
-[Exposed=Window, Pref="dom.webgl2.enabled"]
+[Exposed=Window, Pref="dom_webgl2_enabled"]
 interface WebGLQuery : WebGLObject {
 };
diff --git a/components/script/dom/webidls/WebGLSampler.webidl b/components/script/dom/webidls/WebGLSampler.webidl
index 90c66b65a1d..4669aebeabd 100644
--- a/components/script/dom/webidls/WebGLSampler.webidl
+++ b/components/script/dom/webidls/WebGLSampler.webidl
@@ -6,6 +6,6 @@
 // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.8
 //
 
-[Exposed=Window, Pref="dom.webgl2.enabled"]
+[Exposed=Window, Pref="dom_webgl2_enabled"]
 interface WebGLSampler : WebGLObject {
 };
diff --git a/components/script/dom/webidls/WebGLSync.webidl b/components/script/dom/webidls/WebGLSync.webidl
index f8cd33ef9ce..66640a888f0 100644
--- a/components/script/dom/webidls/WebGLSync.webidl
+++ b/components/script/dom/webidls/WebGLSync.webidl
@@ -6,6 +6,6 @@
 // https://www.khronos.org/registry/webgl/specs/latest/2.0/#3.7.14
 //
 
-[Exposed=Window, Pref="dom.webgl2.enabled"]
+[Exposed=Window, Pref="dom_webgl2_enabled"]
 interface WebGLSync : WebGLObject {
 };
diff --git a/components/script/dom/webidls/WebGLTransformFeedback.webidl b/components/script/dom/webidls/WebGLTransformFeedback.webidl
index 871c0f15c7b..ee666366dd4 100644
--- a/components/script/dom/webidls/WebGLTransformFeedback.webidl
+++ b/components/script/dom/webidls/WebGLTransformFeedback.webidl
@@ -6,6 +6,6 @@
 // https://www.khronos.org/registry/webgl/specs/latest/2.0/#3.7.15
 //
 
-[Exposed=(Window), Pref="dom.webgl2.enabled"]
+[Exposed=(Window), Pref="dom_webgl2_enabled"]
 interface WebGLTransformFeedback : WebGLObject {
 };
diff --git a/components/script/dom/webidls/WebGLVertexArrayObject.webidl b/components/script/dom/webidls/WebGLVertexArrayObject.webidl
index a42d8cbe051..c6649e17ef8 100644
--- a/components/script/dom/webidls/WebGLVertexArrayObject.webidl
+++ b/components/script/dom/webidls/WebGLVertexArrayObject.webidl
@@ -6,6 +6,6 @@
 // https://www.khronos.org/registry/webgl/specs/latest/2.0/#3.7.17
 //
 
-[Exposed=(Window), Pref="dom.webgl2.enabled"]
+[Exposed=(Window), Pref="dom_webgl2_enabled"]
 interface WebGLVertexArrayObject : WebGLObject {
 };
diff --git a/components/script/dom/webidls/WebGPU.webidl b/components/script/dom/webidls/WebGPU.webidl
index 5f0572c768a..41bee4718cb 100644
--- a/components/script/dom/webidls/WebGPU.webidl
+++ b/components/script/dom/webidls/WebGPU.webidl
@@ -16,7 +16,7 @@ dictionary GPUObjectDescriptorBase {
     USVString label = "";
 };
 
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface GPUSupportedLimits {
     readonly attribute unsigned long maxTextureDimension1D;
     readonly attribute unsigned long maxTextureDimension2D;
@@ -52,17 +52,17 @@ interface GPUSupportedLimits {
     readonly attribute unsigned long maxComputeWorkgroupsPerDimension;
 };
 
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface GPUSupportedFeatures {
     readonly setlike<DOMString>;
 };
 
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface WGSLLanguageFeatures {
     readonly setlike<DOMString>;
 };
 
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface GPUAdapterInfo {
     readonly attribute DOMString vendor;
     readonly attribute DOMString architecture;
@@ -71,13 +71,13 @@ interface GPUAdapterInfo {
 };
 
 interface mixin NavigatorGPU {
-    [SameObject, Pref="dom.webgpu.enabled", Exposed=(Window /* ,DedicatedWorker */)] readonly attribute GPU gpu;
+    [SameObject, Pref="dom_webgpu_enabled", Exposed=(Window /* ,DedicatedWorker */)] readonly attribute GPU gpu;
 };
 
 Navigator includes NavigatorGPU;
 WorkerNavigator includes NavigatorGPU;
 
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface GPU {
     [NewObject]
     Promise<GPUAdapter?> requestAdapter(optional GPURequestAdapterOptions options = {});
@@ -95,7 +95,7 @@ enum GPUPowerPreference {
     "high-performance"
 };
 
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface GPUAdapter {
     [SameObject] readonly attribute GPUSupportedFeatures features;
     [SameObject] readonly attribute GPUSupportedLimits limits;
@@ -129,7 +129,7 @@ enum GPUFeatureName {
     "dual-source-blending",
 };
 
-[Exposed=(Window, DedicatedWorker), /*Serializable,*/ Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), /*Serializable,*/ Pref="dom_webgpu_enabled"]
 interface GPUDevice: EventTarget {
     [SameObject] readonly attribute GPUSupportedFeatures features;
     [SameObject] readonly attribute GPUSupportedLimits limits;
@@ -170,7 +170,7 @@ interface GPUDevice: EventTarget {
 };
 GPUDevice includes GPUObjectBase;
 
-[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom_webgpu_enabled"]
 interface GPUBuffer {
     readonly attribute GPUSize64Out size;
     readonly attribute GPUFlagsConstant usage;
@@ -201,7 +201,7 @@ dictionary GPUBufferDescriptor : GPUObjectDescriptorBase {
 };
 
 typedef [EnforceRange] unsigned long GPUBufferUsageFlags;
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 namespace GPUBufferUsage {
     const GPUFlagsConstant MAP_READ      = 0x0001;
     const GPUFlagsConstant MAP_WRITE     = 0x0002;
@@ -216,13 +216,13 @@ namespace GPUBufferUsage {
 };
 
 typedef [EnforceRange] unsigned long GPUMapModeFlags;
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 namespace GPUMapMode {
     const GPUFlagsConstant READ  = 0x0001;
     const GPUFlagsConstant WRITE = 0x0002;
 };
 
-[Exposed=(Window, DedicatedWorker), Serializable , Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Serializable , Pref="dom_webgpu_enabled"]
 interface GPUTexture {
     [Throws, NewObject]
     GPUTextureView createView(optional GPUTextureViewDescriptor descriptor = {});
@@ -257,7 +257,7 @@ enum GPUTextureDimension {
 };
 
 typedef [EnforceRange] unsigned long GPUTextureUsageFlags;
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface GPUTextureUsage {
     const GPUTextureUsageFlags COPY_SRC          = 0x01;
     const GPUTextureUsageFlags COPY_DST          = 0x02;
@@ -266,7 +266,7 @@ interface GPUTextureUsage {
     const GPUTextureUsageFlags RENDER_ATTACHMENT = 0x10;
 };
 
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface GPUTextureView {
 };
 GPUTextureView includes GPUObjectBase;
@@ -418,7 +418,7 @@ enum GPUTextureFormat {
     "astc-12x12-unorm-srgb",
 };
 
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface GPUSampler {
 };
 GPUSampler includes GPUObjectBase;
@@ -458,7 +458,7 @@ enum GPUCompareFunction {
     "always"
 };
 
-[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom_webgpu_enabled"]
 interface GPUBindGroupLayout {
 };
 GPUBindGroupLayout includes GPUObjectBase;
@@ -479,7 +479,7 @@ dictionary GPUBindGroupLayoutEntry {
 };
 
 typedef [EnforceRange] unsigned long GPUShaderStageFlags;
-[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom_webgpu_enabled"]
 interface GPUShaderStage {
     const GPUShaderStageFlags VERTEX = 1;
     const GPUShaderStageFlags FRAGMENT = 2;
@@ -537,7 +537,7 @@ dictionary GPUStorageTextureBindingLayout {
 dictionary GPUExternalTextureBindingLayout {
 };
 
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface GPUBindGroup {
 };
 GPUBindGroup includes GPUObjectBase;
@@ -560,7 +560,7 @@ dictionary GPUBufferBinding {
     GPUSize64 size;
 };
 
-[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom_webgpu_enabled"]
 interface GPUPipelineLayout {
 };
 GPUPipelineLayout includes GPUObjectBase;
@@ -569,7 +569,7 @@ dictionary GPUPipelineLayoutDescriptor : GPUObjectDescriptorBase {
     required sequence<GPUBindGroupLayout> bindGroupLayouts;
 };
 
-[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom_webgpu_enabled"]
 interface GPUShaderModule {
     Promise<GPUCompilationInfo> getCompilationInfo();
 };
@@ -587,7 +587,7 @@ enum GPUCompilationMessageType {
     "info"
 };
 
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface GPUCompilationMessage {
     readonly attribute DOMString message;
     readonly attribute GPUCompilationMessageType type;
@@ -597,13 +597,13 @@ interface GPUCompilationMessage {
     readonly attribute unsigned long long length;
 };
 
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface GPUCompilationInfo {
     //readonly attribute FrozenArray<GPUCompilationMessage> messages;
     readonly attribute any messages;
 };
 
-[Exposed=(Window, Worker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, Worker), Pref="dom_webgpu_enabled"]
 interface GPUPipelineError : DOMException {
     constructor(optional DOMString message = "", GPUPipelineErrorInit options);
     readonly attribute GPUPipelineErrorReason reason;
@@ -638,7 +638,7 @@ dictionary GPUProgrammableStage {
 
 typedef double GPUPipelineConstantValue; // May represent WGSL's bool, f32, i32, u32, and f16 if enabled.
 
-[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom_webgpu_enabled"]
 interface GPUComputePipeline {
 };
 GPUComputePipeline includes GPUObjectBase;
@@ -648,7 +648,7 @@ dictionary GPUComputePipelineDescriptor : GPUPipelineDescriptorBase {
     required GPUProgrammableStage compute;
 };
 
-[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom_webgpu_enabled"]
 interface GPURenderPipeline {
 };
 GPURenderPipeline includes GPUObjectBase;
@@ -712,7 +712,7 @@ dictionary GPUBlendState {
 };
 
 typedef [EnforceRange] unsigned long GPUColorWriteFlags;
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface GPUColorWrite {
     const GPUColorWriteFlags RED   = 0x1;
     const GPUColorWriteFlags GREEN = 0x2;
@@ -873,7 +873,7 @@ dictionary GPUImageCopyExternalImage {
     boolean flipY = false;
 };
 
-[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom_webgpu_enabled"]
 interface GPUCommandBuffer {
 };
 GPUCommandBuffer includes GPUObjectBase;
@@ -881,7 +881,7 @@ GPUCommandBuffer includes GPUObjectBase;
 dictionary GPUCommandBufferDescriptor : GPUObjectDescriptorBase {
 };
 
-[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom_webgpu_enabled"]
 interface GPUCommandEncoder {
     [NewObject]
     GPUComputePassEncoder beginComputePass(optional GPUComputePassDescriptor descriptor = {});
@@ -939,11 +939,11 @@ dictionary GPUCommandEncoderDescriptor : GPUObjectDescriptorBase {
     boolean measureExecutionTime = false;
 };
 
-[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom_webgpu_enabled"]
 interface GPUComputePassEncoder {
     undefined setPipeline(GPUComputePipeline pipeline);
     undefined dispatchWorkgroups(GPUSize32 x, optional GPUSize32 y = 1, optional GPUSize32 z = 1);
-    //[Pref="dom.webgpu.indirect-dispatch.enabled"]
+    //[Pref="dom_webgpu_indirect-dispatch.enabled"]
     undefined dispatchWorkgroupsIndirect(GPUBuffer indirectBuffer, GPUSize64 indirectOffset);
 
     undefined end();
@@ -954,7 +954,7 @@ GPUComputePassEncoder includes GPUProgrammablePassEncoder;
 dictionary GPUComputePassDescriptor : GPUObjectDescriptorBase {
 };
 
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface GPURenderPassEncoder {
     undefined setViewport(float x, float y,
                           float width, float height,
@@ -1063,13 +1063,13 @@ interface mixin GPURenderEncoderBase {
                           optional GPUSignedOffset32 baseVertex = 0,
                           optional GPUSize32 firstInstance = 0);
 
-    //[Pref="dom.webgpu.indirect-dispatch.enabled"]
+    //[Pref="dom_webgpu_indirect-dispatch.enabled"]
     undefined drawIndirect(GPUBuffer indirectBuffer, GPUSize64 indirectOffset);
-    //[Pref="dom.webgpu.indirect-dispatch.enabled"]
+    //[Pref="dom_webgpu_indirect-dispatch.enabled"]
     undefined drawIndexedIndirect(GPUBuffer indirectBuffer, GPUSize64 indirectOffset);
 };
 
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface GPURenderBundle {
 };
 GPURenderBundle includes GPUObjectBase;
@@ -1077,7 +1077,7 @@ GPURenderBundle includes GPUObjectBase;
 dictionary GPURenderBundleDescriptor : GPUObjectDescriptorBase {
 };
 
-[Exposed=(Window, DedicatedWorker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Pref="dom_webgpu_enabled"]
 interface GPURenderBundleEncoder {
     GPURenderBundle finish(optional GPURenderBundleDescriptor descriptor = {});
 };
@@ -1090,7 +1090,7 @@ dictionary GPURenderBundleEncoderDescriptor : GPURenderPassLayout {
     boolean stencilReadOnly = false;
 };
 
-[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom_webgpu_enabled"]
 interface GPUQueue {
     undefined submit(sequence<GPUCommandBuffer> buffers);
 
@@ -1119,7 +1119,7 @@ interface GPUQueue {
 };
 GPUQueue includes GPUObjectBase;
 
-[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom.webgpu.enabled"]
+[Exposed=(Window, DedicatedWorker), Serializable, Pref="dom_webgpu_enabled"]
 interface GPUQuerySet {
     undefined destroy();
 };
@@ -1173,7 +1173,7 @@ enum GPUDeviceLostReason {
     "destroyed",
 };
 
-[Exposed=(Window, Worker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, Worker), Pref="dom_webgpu_enabled"]
 interface GPUDeviceLostInfo {
     readonly attribute GPUDeviceLostReason reason;
     readonly attribute DOMString message;
@@ -1183,24 +1183,24 @@ partial interface GPUDevice {
     readonly attribute Promise<GPUDeviceLostInfo> lost;
 };
 
-[Exposed=(Window, Worker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, Worker), Pref="dom_webgpu_enabled"]
 interface GPUError {
     readonly attribute DOMString message;
 };
 
-[Exposed=(Window, Worker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, Worker), Pref="dom_webgpu_enabled"]
 interface GPUValidationError
         : GPUError {
     constructor(DOMString message);
 };
 
-[Exposed=(Window, Worker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, Worker), Pref="dom_webgpu_enabled"]
 interface GPUOutOfMemoryError
         : GPUError {
     constructor(DOMString message);
 };
 
-[Exposed=(Window, Worker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, Worker), Pref="dom_webgpu_enabled"]
 interface GPUInternalError
         : GPUError {
     constructor(DOMString message);
@@ -1218,7 +1218,7 @@ partial interface GPUDevice {
     Promise<GPUError?> popErrorScope();
 };
 
-[Exposed=(Window, Worker), Pref="dom.webgpu.enabled"]
+[Exposed=(Window, Worker), Pref="dom_webgpu_enabled"]
 interface GPUUncapturedErrorEvent : Event {
     constructor(
         DOMString type,
diff --git a/components/script/dom/webidls/Window.webidl b/components/script/dom/webidls/Window.webidl
index 84871494d2b..64d7563b38e 100644
--- a/components/script/dom/webidls/Window.webidl
+++ b/components/script/dom/webidls/Window.webidl
@@ -15,7 +15,7 @@
   [PutForwards=href, LegacyUnforgeable, CrossOriginReadable, CrossOriginWritable]
     readonly attribute Location location;
   readonly attribute History history;
-  [Pref="dom.customelements.enabled"]
+  [Pref="dom_customelements_enabled"]
   readonly attribute CustomElementRegistry customElements;
   //[Replaceable] readonly attribute BarProp locationbar;
   //[Replaceable] readonly attribute BarProp menubar;
@@ -136,11 +136,11 @@ partial interface Window {
 
 // Proprietary extensions.
 partial interface Window {
-  [Pref="dom.servo_helpers.enabled"]
+  [Pref="dom_servo_helpers_enabled"]
   undefined debug(DOMString arg);
-  [Pref="dom.servo_helpers.enabled"]
+  [Pref="dom_servo_helpers_enabled"]
   undefined gc();
-  [Pref="dom.servo_helpers.enabled"]
+  [Pref="dom_servo_helpers_enabled"]
   undefined js_backtrace();
 };
 
@@ -168,13 +168,13 @@ callback FrameRequestCallback = undefined (DOMHighResTimeStamp time);
 
 // https://webbluetoothcg.github.io/web-bluetooth/tests#test-interfaces
 partial interface Window {
-   [Pref="dom.bluetooth.testing.enabled", Exposed=Window]
+   [Pref="dom_bluetooth_testing_enabled", Exposed=Window]
    readonly attribute TestRunner testRunner;
    //readonly attribute EventSender eventSender;
 };
 
 partial interface Window {
-   [Pref="css.animations.testing.enabled"]
+   [Pref="css_animations_testing_enabled"]
    readonly attribute unsigned long runningAnimationCount;
 };
 
diff --git a/components/script/dom/webidls/WindowOrWorkerGlobalScope.webidl b/components/script/dom/webidls/WindowOrWorkerGlobalScope.webidl
index dbcce406a43..d9204c11774 100644
--- a/components/script/dom/webidls/WindowOrWorkerGlobalScope.webidl
+++ b/components/script/dom/webidls/WindowOrWorkerGlobalScope.webidl
@@ -24,7 +24,7 @@ interface mixin WindowOrWorkerGlobalScope {
   undefined queueMicrotask(VoidFunction callback);
 
   // ImageBitmap
-  [Pref="dom.imagebitmap.enabled"]
+  [Pref="dom_imagebitmap_enabled"]
   Promise<ImageBitmap> createImageBitmap(ImageBitmapSource image, optional ImageBitmapOptions options = {});
   // Promise<ImageBitmap> createImageBitmap(
   //   ImageBitmapSource image, long sx, long sy, long sw, long sh, optional ImageBitmapOptions options);
diff --git a/components/script/dom/webidls/WorkerNavigator.webidl b/components/script/dom/webidls/WorkerNavigator.webidl
index 3de4be96ebc..33ddfade93d 100644
--- a/components/script/dom/webidls/WorkerNavigator.webidl
+++ b/components/script/dom/webidls/WorkerNavigator.webidl
@@ -14,6 +14,6 @@ WorkerNavigator includes NavigatorConcurrentHardware;
 
 [Exposed=(Worker)]
 partial interface WorkerNavigator {
-  [Pref="dom.permissions.enabled"] readonly attribute Permissions permissions;
+  [Pref="dom_permissions_enabled"] readonly attribute Permissions permissions;
 };
 
diff --git a/components/script/dom/webidls/Worklet.webidl b/components/script/dom/webidls/Worklet.webidl
index 249f9c9d470..a656c1e3865 100644
--- a/components/script/dom/webidls/Worklet.webidl
+++ b/components/script/dom/webidls/Worklet.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://drafts.css-houdini.org/worklets/#worklet
-[Pref="dom.worklet.enabled", Exposed=(Window)]
+[Pref="dom_worklet_enabled", Exposed=(Window)]
 interface Worklet {
     [NewObject] Promise<undefined> addModule(USVString moduleURL, optional WorkletOptions options = {});
 };
diff --git a/components/script/dom/webidls/WorkletGlobalScope.webidl b/components/script/dom/webidls/WorkletGlobalScope.webidl
index 21f7a7e0af0..33283c84161 100644
--- a/components/script/dom/webidls/WorkletGlobalScope.webidl
+++ b/components/script/dom/webidls/WorkletGlobalScope.webidl
@@ -5,6 +5,6 @@
 // https://drafts.css-houdini.org/worklets/#workletglobalscope
 // TODO: The spec IDL doesn't make this a subclass of EventTarget
 //       https://github.com/whatwg/html/issues/2611
-[Pref="dom.worklet.enabled", Exposed=Worklet]
+[Pref="dom_worklet_enabled", Exposed=Worklet]
 interface WorkletGlobalScope: GlobalScope {
 };
diff --git a/components/script/dom/webidls/XPathEvaluator.webidl b/components/script/dom/webidls/XPathEvaluator.webidl
index 8586b19232b..ebb505c104c 100644
--- a/components/script/dom/webidls/XPathEvaluator.webidl
+++ b/components/script/dom/webidls/XPathEvaluator.webidl
@@ -4,13 +4,13 @@
 
 // https://dom.spec.whatwg.org/#mixin-xpathevaluatorbase
 interface mixin XPathEvaluatorBase {
-  [NewObject, Throws, Pref="dom.xpath.enabled"] XPathExpression createExpression(
+  [NewObject, Throws, Pref="dom_xpath_enabled"] XPathExpression createExpression(
     DOMString expression,
     optional XPathNSResolver? resolver = null
   );
   Node createNSResolver(Node nodeResolver); // legacy
   // XPathResult.ANY_TYPE = 0
-  [Throws, Pref="dom.xpath.enabled"] XPathResult evaluate(
+  [Throws, Pref="dom_xpath_enabled"] XPathResult evaluate(
     DOMString expression,
     Node contextNode,
     optional XPathNSResolver? resolver = null,
@@ -22,7 +22,7 @@ interface mixin XPathEvaluatorBase {
 Document includes XPathEvaluatorBase;
 
 // https://dom.spec.whatwg.org/#interface-xpathevaluator
-[Exposed=Window, Pref="dom.xpath.enabled"]
+[Exposed=Window, Pref="dom_xpath_enabled"]
 interface XPathEvaluator {
   constructor();
 };
diff --git a/components/script/dom/webidls/XPathExpression.webidl b/components/script/dom/webidls/XPathExpression.webidl
index bf5ba2b83aa..29cbd23e757 100644
--- a/components/script/dom/webidls/XPathExpression.webidl
+++ b/components/script/dom/webidls/XPathExpression.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://dom.spec.whatwg.org/#interface-xpathexpression
-[Exposed=Window, Pref="dom.xpath.enabled"]
+[Exposed=Window, Pref="dom_xpath_enabled"]
 interface XPathExpression {
   // XPathResult.ANY_TYPE = 0
   [Throws] XPathResult evaluate(
diff --git a/components/script/dom/webidls/XPathResult.webidl b/components/script/dom/webidls/XPathResult.webidl
index 25e87e3024a..ed0e9804ca4 100644
--- a/components/script/dom/webidls/XPathResult.webidl
+++ b/components/script/dom/webidls/XPathResult.webidl
@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://dom.spec.whatwg.org/#interface-xpathresult
-[Exposed=Window, Pref="dom.xpath.enabled"]
+[Exposed=Window, Pref="dom_xpath_enabled"]
 interface XPathResult {
   const unsigned short ANY_TYPE = 0;
   const unsigned short NUMBER_TYPE = 1;
diff --git a/components/script/dom/webidls/XRBoundedReferenceSpace.webidl b/components/script/dom/webidls/XRBoundedReferenceSpace.webidl
index c028f740c87..9bf63f7f685 100644
--- a/components/script/dom/webidls/XRBoundedReferenceSpace.webidl
+++ b/components/script/dom/webidls/XRBoundedReferenceSpace.webidl
@@ -6,7 +6,7 @@
 
 // https://immersive-web.github.io/webxr/#xrboundedreferencespace-interface
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRBoundedReferenceSpace : XRReferenceSpace {
   readonly attribute /*FrozenArray<DOMPointReadOnly>*/ any boundsGeometry;
 };
diff --git a/components/script/dom/webidls/XRCompositionLayer.webidl b/components/script/dom/webidls/XRCompositionLayer.webidl
index e8cedf71240..bdfe3435965 100644
--- a/components/script/dom/webidls/XRCompositionLayer.webidl
+++ b/components/script/dom/webidls/XRCompositionLayer.webidl
@@ -8,7 +8,7 @@
 // https://github.com/servo/servo/issues/27493
 
 // https://immersive-web.github.io/layers/#xrcompositionlayer
-[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_layers_enabled"]
 interface XRCompositionLayer : XRLayer {
 //   readonly attribute XRLayerLayout layout;
 //
diff --git a/components/script/dom/webidls/XRCubeLayer.webidl b/components/script/dom/webidls/XRCubeLayer.webidl
index 1b213f34be3..30744201a87 100644
--- a/components/script/dom/webidls/XRCubeLayer.webidl
+++ b/components/script/dom/webidls/XRCubeLayer.webidl
@@ -9,7 +9,7 @@
 
 // https://immersive-web.github.io/layers/#xrcubelayer
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_layers_enabled"]
 interface XRCubeLayer : XRCompositionLayer {
 //   attribute XRSpace space;
 //   attribute DOMPointReadOnly orientation;
diff --git a/components/script/dom/webidls/XRCylinderLayer.webidl b/components/script/dom/webidls/XRCylinderLayer.webidl
index e290aecdee4..c20801f81a0 100644
--- a/components/script/dom/webidls/XRCylinderLayer.webidl
+++ b/components/script/dom/webidls/XRCylinderLayer.webidl
@@ -8,7 +8,7 @@
 // https://github.com/servo/servo/issues/27493
 
 // https://immersive-web.github.io/layers/#xrcylinderlayer
-[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_layers_enabled"]
 interface XRCylinderLayer : XRCompositionLayer {
 //   attribute XRSpace space;
 //   attribute XRRigidTransform transform;
diff --git a/components/script/dom/webidls/XREquirectLayer.webidl b/components/script/dom/webidls/XREquirectLayer.webidl
index f7eeb327b9a..7b1d1584d62 100644
--- a/components/script/dom/webidls/XREquirectLayer.webidl
+++ b/components/script/dom/webidls/XREquirectLayer.webidl
@@ -8,7 +8,7 @@
 // https://github.com/servo/servo/issues/27493
 
 // https://immersive-web.github.io/layers/#xrequirectlayer
-[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_layers_enabled"]
 interface XREquirectLayer : XRCompositionLayer {
 //   attribute XRSpace space;
 //   attribute XRRigidTransform transform;
diff --git a/components/script/dom/webidls/XRFrame.webidl b/components/script/dom/webidls/XRFrame.webidl
index 2e05028ec0c..d5ec4b6ef21 100644
--- a/components/script/dom/webidls/XRFrame.webidl
+++ b/components/script/dom/webidls/XRFrame.webidl
@@ -6,7 +6,7 @@
 
 // https://immersive-web.github.io/webxr/#xrframe-interface
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRFrame {
   [SameObject] readonly attribute XRSession session;
   readonly attribute DOMHighResTimeStamp predictedDisplayTime;
@@ -15,12 +15,12 @@ interface XRFrame {
   [Throws] XRPose? getPose(XRSpace space, XRSpace baseSpace);
 
   // WebXR Hand Input
-  [Pref="dom.webxr.hands.enabled", Throws]
+  [Pref="dom_webxr_hands_enabled", Throws]
   XRJointPose? getJointPose(XRJointSpace joint, XRSpace baseSpace);
-  [Pref="dom.webxr.hands.enabled", Throws]
+  [Pref="dom_webxr_hands_enabled", Throws]
   boolean fillJointRadii(sequence<XRJointSpace> jointSpaces, Float32Array radii);
 
-  [Pref="dom.webxr.hands.enabled", Throws]
+  [Pref="dom_webxr_hands_enabled", Throws]
   boolean fillPoses(sequence<XRSpace> spaces, XRSpace baseSpace, Float32Array transforms);
 
   // WebXR Hit Test
diff --git a/components/script/dom/webidls/XRHand.webidl b/components/script/dom/webidls/XRHand.webidl
index ad46e719f2b..6749eab8dd5 100644
--- a/components/script/dom/webidls/XRHand.webidl
+++ b/components/script/dom/webidls/XRHand.webidl
@@ -39,7 +39,7 @@ enum XRHandJoint {
     "pinky-finger-tip"
 };
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.hands.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_hands_enabled"]
 interface XRHand {
     iterable<XRHandJoint, XRJointSpace>;
 
diff --git a/components/script/dom/webidls/XRInputSource.webidl b/components/script/dom/webidls/XRInputSource.webidl
index 820f24c363f..7b82b050777 100644
--- a/components/script/dom/webidls/XRInputSource.webidl
+++ b/components/script/dom/webidls/XRInputSource.webidl
@@ -19,7 +19,7 @@ enum XRTargetRayMode {
   "transient-pointer"
 };
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRInputSource {
   readonly attribute XRHandedness handedness;
   readonly attribute XRTargetRayMode targetRayMode;
@@ -32,6 +32,6 @@ interface XRInputSource {
   [SameObject] readonly attribute Gamepad? gamepad;
 
   // Hand Input
-  [Pref="dom.webxr.hands.enabled"]
+  [Pref="dom_webxr_hands_enabled"]
   readonly attribute XRHand? hand;
 };
diff --git a/components/script/dom/webidls/XRInputSourceArray.webidl b/components/script/dom/webidls/XRInputSourceArray.webidl
index 5987c0039d3..093eab67ed9 100644
--- a/components/script/dom/webidls/XRInputSourceArray.webidl
+++ b/components/script/dom/webidls/XRInputSourceArray.webidl
@@ -6,7 +6,7 @@
 
 // https://immersive-web.github.io/webxr/#xrinputsourcearray-interface
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRInputSourceArray {
   iterable<XRInputSource>;
   readonly attribute unsigned long length;
diff --git a/components/script/dom/webidls/XRInputSourceEvent.webidl b/components/script/dom/webidls/XRInputSourceEvent.webidl
index e2cb1b394c9..11055b3f247 100644
--- a/components/script/dom/webidls/XRInputSourceEvent.webidl
+++ b/components/script/dom/webidls/XRInputSourceEvent.webidl
@@ -6,7 +6,7 @@
 
 // https://immersive-web.github.io/webxr/#xrinputsourceevent-interface
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRInputSourceEvent : Event {
   [Throws] constructor(DOMString type, XRInputSourceEventInit eventInitDict);
   [SameObject] readonly attribute XRFrame frame;
diff --git a/components/script/dom/webidls/XRInputSourcesChangeEvent.webidl b/components/script/dom/webidls/XRInputSourcesChangeEvent.webidl
index 25a4885cca3..f6b65d12a09 100644
--- a/components/script/dom/webidls/XRInputSourcesChangeEvent.webidl
+++ b/components/script/dom/webidls/XRInputSourcesChangeEvent.webidl
@@ -6,7 +6,7 @@
 
 // https://immersive-web.github.io/webxr/#xrinputsourceschangedevent-interface
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.test"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_test"]
 interface XRInputSourcesChangeEvent : Event {
   constructor(DOMString type, XRInputSourcesChangeEventInit eventInitDict);
   [SameObject] readonly attribute XRSession session;
diff --git a/components/script/dom/webidls/XRJointPose.webidl b/components/script/dom/webidls/XRJointPose.webidl
index e824745588e..73bde0ca6e6 100644
--- a/components/script/dom/webidls/XRJointPose.webidl
+++ b/components/script/dom/webidls/XRJointPose.webidl
@@ -6,7 +6,7 @@
 
 // https://github.com/immersive-web/webxr-hands-input/blob/master/explainer.md
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.hands.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_hands_enabled"]
 interface XRJointPose: XRPose {
     readonly attribute float? radius;
 };
diff --git a/components/script/dom/webidls/XRJointSpace.webidl b/components/script/dom/webidls/XRJointSpace.webidl
index 7326e9990a1..2eeca7edc15 100644
--- a/components/script/dom/webidls/XRJointSpace.webidl
+++ b/components/script/dom/webidls/XRJointSpace.webidl
@@ -6,7 +6,7 @@
 
 // https://github.com/immersive-web/webxr-hands-input/blob/master/explainer.md
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.hands.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_hands_enabled"]
 interface XRJointSpace: XRSpace {
   readonly attribute XRHandJoint jointName;
 };
diff --git a/components/script/dom/webidls/XRLayer.webidl b/components/script/dom/webidls/XRLayer.webidl
index 122946defb9..fdc9b2bee3a 100644
--- a/components/script/dom/webidls/XRLayer.webidl
+++ b/components/script/dom/webidls/XRLayer.webidl
@@ -5,5 +5,5 @@
 // skip-unless CARGO_FEATURE_WEBXR
 
 // https://immersive-web.github.io/webxr/#xrlayer
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRLayer : EventTarget {};
diff --git a/components/script/dom/webidls/XRLayerEvent.webidl b/components/script/dom/webidls/XRLayerEvent.webidl
index e45f116da34..553a70fcaec 100644
--- a/components/script/dom/webidls/XRLayerEvent.webidl
+++ b/components/script/dom/webidls/XRLayerEvent.webidl
@@ -5,7 +5,7 @@
 // skip-unless CARGO_FEATURE_WEBXR
 
 // https://immersive-web.github.io/layers/#xrlayerevent-interface
-[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_layers_enabled"]
 interface XRLayerEvent : Event {
   constructor(DOMString type, XRLayerEventInit eventInitDict);
   [SameObject] readonly attribute XRLayer layer;
diff --git a/components/script/dom/webidls/XRMediaBinding.webidl b/components/script/dom/webidls/XRMediaBinding.webidl
index 4c3bfc91e80..558aa0596c3 100644
--- a/components/script/dom/webidls/XRMediaBinding.webidl
+++ b/components/script/dom/webidls/XRMediaBinding.webidl
@@ -5,7 +5,7 @@
 // skip-unless CARGO_FEATURE_WEBXR
 
 // https://immersive-web.github.io/layers/#xrmediabindingtype
-[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_layers_enabled"]
 interface XRMediaBinding {
   [Throws] constructor(XRSession session);
 
diff --git a/components/script/dom/webidls/XRPose.webidl b/components/script/dom/webidls/XRPose.webidl
index dab2d9e7af9..2ac5f372cdd 100644
--- a/components/script/dom/webidls/XRPose.webidl
+++ b/components/script/dom/webidls/XRPose.webidl
@@ -6,7 +6,7 @@
 
 // https://immersive-web.github.io/webxr/#xrpose-interface
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRPose {
   [SameObject] readonly attribute XRRigidTransform transform;
   [SameObject] readonly attribute DOMPointReadOnly? linearVelocity;
diff --git a/components/script/dom/webidls/XRProjectionLayer.webidl b/components/script/dom/webidls/XRProjectionLayer.webidl
index 0c812948795..bdb9de13dd2 100644
--- a/components/script/dom/webidls/XRProjectionLayer.webidl
+++ b/components/script/dom/webidls/XRProjectionLayer.webidl
@@ -8,7 +8,7 @@
 // https://github.com/servo/servo/issues/27493
 
 // https://immersive-web.github.io/layers/#xrprojectionlayer
-[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_layers_enabled"]
 interface XRProjectionLayer : XRCompositionLayer {
 //   readonly attribute boolean ignoreDepthValues;
 };
diff --git a/components/script/dom/webidls/XRQuadLayer.webidl b/components/script/dom/webidls/XRQuadLayer.webidl
index a4c43b0b62e..0b4afcac9be 100644
--- a/components/script/dom/webidls/XRQuadLayer.webidl
+++ b/components/script/dom/webidls/XRQuadLayer.webidl
@@ -8,7 +8,7 @@
 // https://github.com/servo/servo/issues/27493
 
 // https://immersive-web.github.io/layers/#xrquadlayer
-[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_layers_enabled"]
 interface XRQuadLayer : XRCompositionLayer {
 //   attribute XRSpace space;
 //   attribute XRRigidTransform transform;
diff --git a/components/script/dom/webidls/XRRay.webidl b/components/script/dom/webidls/XRRay.webidl
index 748bd085147..b5fd7ed3494 100644
--- a/components/script/dom/webidls/XRRay.webidl
+++ b/components/script/dom/webidls/XRRay.webidl
@@ -13,7 +13,7 @@ dictionary XRRayDirectionInit {
   double w = 0;
 };
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRRay {
   [Throws] constructor(optional DOMPointInit origin = {}, optional XRRayDirectionInit direction = {});
   [Throws] constructor(XRRigidTransform transform);
diff --git a/components/script/dom/webidls/XRReferenceSpace.webidl b/components/script/dom/webidls/XRReferenceSpace.webidl
index ad9bd41659c..aad31702f01 100644
--- a/components/script/dom/webidls/XRReferenceSpace.webidl
+++ b/components/script/dom/webidls/XRReferenceSpace.webidl
@@ -14,7 +14,7 @@ enum XRReferenceSpaceType {
   "unbounded"
 };
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRReferenceSpace : XRSpace {
   [NewObject] XRReferenceSpace getOffsetReferenceSpace(XRRigidTransform originOffset);
 
diff --git a/components/script/dom/webidls/XRReferenceSpaceEvent.webidl b/components/script/dom/webidls/XRReferenceSpaceEvent.webidl
index a15e7aba316..b9075294d1e 100644
--- a/components/script/dom/webidls/XRReferenceSpaceEvent.webidl
+++ b/components/script/dom/webidls/XRReferenceSpaceEvent.webidl
@@ -6,7 +6,7 @@
 
 // https://immersive-web.github.io/webxr/#xrreferencespaceevent-interface
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRReferenceSpaceEvent : Event {
   [Throws] constructor(DOMString type, XRReferenceSpaceEventInit eventInitDict);
   [SameObject] readonly attribute XRReferenceSpace referenceSpace;
diff --git a/components/script/dom/webidls/XRRenderState.webidl b/components/script/dom/webidls/XRRenderState.webidl
index d02ab20646a..ff91e0d2fea 100644
--- a/components/script/dom/webidls/XRRenderState.webidl
+++ b/components/script/dom/webidls/XRRenderState.webidl
@@ -14,7 +14,7 @@ dictionary XRRenderStateInit {
   sequence<XRLayer>? layers;
 };
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"] interface XRRenderState {
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"] interface XRRenderState {
   readonly attribute double depthNear;
   readonly attribute double depthFar;
   readonly attribute double? inlineVerticalFieldOfView;
diff --git a/components/script/dom/webidls/XRRigidTransform.webidl b/components/script/dom/webidls/XRRigidTransform.webidl
index 85fb73509fe..11fbf9615b7 100644
--- a/components/script/dom/webidls/XRRigidTransform.webidl
+++ b/components/script/dom/webidls/XRRigidTransform.webidl
@@ -6,7 +6,7 @@
 
 // https://immersive-web.github.io/webxr/#xrrigidtransform-interface
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRRigidTransform {
   [Throws] constructor(optional DOMPointInit position = {}, optional DOMPointInit orientation = {});
   readonly attribute DOMPointReadOnly position;
diff --git a/components/script/dom/webidls/XRSession.webidl b/components/script/dom/webidls/XRSession.webidl
index a214d6aa133..ccd72b187c6 100644
--- a/components/script/dom/webidls/XRSession.webidl
+++ b/components/script/dom/webidls/XRSession.webidl
@@ -25,7 +25,7 @@ enum XRInteractionMode {
 
 callback XRFrameRequestCallback = undefined (DOMHighResTimeStamp time, XRFrame frame);
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRSession : EventTarget {
   // Attributes
   readonly attribute XRVisibilityState visibilityState;
diff --git a/components/script/dom/webidls/XRSessionEvent.webidl b/components/script/dom/webidls/XRSessionEvent.webidl
index 19ddd9e1b95..4e48f0c6c5c 100644
--- a/components/script/dom/webidls/XRSessionEvent.webidl
+++ b/components/script/dom/webidls/XRSessionEvent.webidl
@@ -6,7 +6,7 @@
 
 // https://immersive-web.github.io/webxr/#xrsessionevent-interface
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRSessionEvent : Event {
   [Throws] constructor(DOMString type, XRSessionEventInit eventInitDict);
   [SameObject] readonly attribute XRSession session;
diff --git a/components/script/dom/webidls/XRSpace.webidl b/components/script/dom/webidls/XRSpace.webidl
index 3f85f4e4a52..236c9164402 100644
--- a/components/script/dom/webidls/XRSpace.webidl
+++ b/components/script/dom/webidls/XRSpace.webidl
@@ -6,7 +6,7 @@
 
 // https://immersive-web.github.io/webxr/#xrspace-interface
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRSpace : EventTarget {
   // XRRigidTransform? getTransformTo(XRSpace other);
 };
diff --git a/components/script/dom/webidls/XRSubImage.webidl b/components/script/dom/webidls/XRSubImage.webidl
index 109ee39513b..3e8efdb24d7 100644
--- a/components/script/dom/webidls/XRSubImage.webidl
+++ b/components/script/dom/webidls/XRSubImage.webidl
@@ -5,7 +5,7 @@
 // skip-unless CARGO_FEATURE_WEBXR
 
 // https://immersive-web.github.io/layers/#xrsubimagetype
-[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_layers_enabled"]
 interface XRSubImage {
   [SameObject] readonly attribute XRViewport viewport;
 };
diff --git a/components/script/dom/webidls/XRSystem.webidl b/components/script/dom/webidls/XRSystem.webidl
index 41682865cd4..ef5537ebdac 100644
--- a/components/script/dom/webidls/XRSystem.webidl
+++ b/components/script/dom/webidls/XRSystem.webidl
@@ -5,7 +5,7 @@
 // skip-unless CARGO_FEATURE_WEBXR
 
 // https://immersive-web.github.io/webxr/#xrsystem-interface
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRSystem: EventTarget {
   // Methods
   Promise<boolean> isSessionSupported(XRSessionMode mode);
@@ -17,7 +17,7 @@ interface XRSystem: EventTarget {
 
 [SecureContext]
 partial interface Navigator {
-  [SameObject, Pref="dom.webxr.enabled"] readonly attribute XRSystem xr;
+  [SameObject, Pref="dom_webxr_enabled"] readonly attribute XRSystem xr;
 };
 
 enum XRSessionMode {
@@ -33,5 +33,5 @@ dictionary XRSessionInit {
 
 partial interface XRSystem {
   // https://github.com/immersive-web/webxr-test-api/
-  [SameObject, Pref="dom.webxr.test"] readonly attribute XRTest test;
+  [SameObject, Pref="dom_webxr_test"] readonly attribute XRTest test;
 };
diff --git a/components/script/dom/webidls/XRTest.webidl b/components/script/dom/webidls/XRTest.webidl
index 2421f873976..710d3520249 100644
--- a/components/script/dom/webidls/XRTest.webidl
+++ b/components/script/dom/webidls/XRTest.webidl
@@ -6,7 +6,7 @@
 
 // https://github.com/immersive-web/webxr-test-api/
 
-[Exposed=Window, Pref="dom.webxr.test"]
+[Exposed=Window, Pref="dom_webxr_test"]
 interface XRTest {
   // Simulates connecting a device to the system.
   // Used to instantiate a fake device for use in tests.
diff --git a/components/script/dom/webidls/XRView.webidl b/components/script/dom/webidls/XRView.webidl
index 2050afe028a..235eb5a6b2b 100644
--- a/components/script/dom/webidls/XRView.webidl
+++ b/components/script/dom/webidls/XRView.webidl
@@ -12,7 +12,7 @@ enum XREye {
   "none",
 };
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRView {
   readonly attribute XREye eye;
   readonly attribute Float32Array projectionMatrix;
diff --git a/components/script/dom/webidls/XRViewerPose.webidl b/components/script/dom/webidls/XRViewerPose.webidl
index 06274c3dfeb..82f57571f8f 100644
--- a/components/script/dom/webidls/XRViewerPose.webidl
+++ b/components/script/dom/webidls/XRViewerPose.webidl
@@ -6,7 +6,7 @@
 
 // https://immersive-web.github.io/webxr/#xrviewerpose-interface
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRViewerPose : XRPose {
   // readonly attribute FrozenArray<XRView> views;
   // workaround until we have FrozenArray
diff --git a/components/script/dom/webidls/XRViewport.webidl b/components/script/dom/webidls/XRViewport.webidl
index 079c2d11e2d..4fc6c7afd86 100644
--- a/components/script/dom/webidls/XRViewport.webidl
+++ b/components/script/dom/webidls/XRViewport.webidl
@@ -6,7 +6,7 @@
 
 // https://immersive-web.github.io/webxr/#xrviewport-interface
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRViewport {
   readonly attribute long x;
   readonly attribute long y;
diff --git a/components/script/dom/webidls/XRWebGLBinding.webidl b/components/script/dom/webidls/XRWebGLBinding.webidl
index 5bcb4b381fa..121c2c1db86 100644
--- a/components/script/dom/webidls/XRWebGLBinding.webidl
+++ b/components/script/dom/webidls/XRWebGLBinding.webidl
@@ -5,7 +5,7 @@
 // skip-unless CARGO_FEATURE_WEBXR
 
 // https://immersive-web.github.io/layers/#XRWebGLBindingtype
-[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_layers_enabled"]
 interface XRWebGLBinding {
   [Throws] constructor(XRSession session, XRWebGLRenderingContext context);
 
diff --git a/components/script/dom/webidls/XRWebGLLayer.webidl b/components/script/dom/webidls/XRWebGLLayer.webidl
index c3bd54b3d03..e69033fcd2a 100644
--- a/components/script/dom/webidls/XRWebGLLayer.webidl
+++ b/components/script/dom/webidls/XRWebGLLayer.webidl
@@ -18,7 +18,7 @@ dictionary XRWebGLLayerInit {
   double framebufferScaleFactor = 1.0;
 };
 
-[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_enabled"]
 interface XRWebGLLayer: XRLayer {
   [Throws] constructor(XRSession session,
               XRWebGLRenderingContext context,
@@ -40,5 +40,5 @@ interface XRWebGLLayer: XRLayer {
 };
 
 partial interface mixin WebGLRenderingContextBase {
-    [Pref="dom.webxr.enabled"] Promise<undefined> makeXRCompatible();
+    [Pref="dom_webxr_enabled"] Promise<undefined> makeXRCompatible();
 };
diff --git a/components/script/dom/webidls/XRWebGLSubImage.webidl b/components/script/dom/webidls/XRWebGLSubImage.webidl
index d93f12ff4c5..83ccdd91166 100644
--- a/components/script/dom/webidls/XRWebGLSubImage.webidl
+++ b/components/script/dom/webidls/XRWebGLSubImage.webidl
@@ -5,7 +5,7 @@
 // skip-unless CARGO_FEATURE_WEBXR
 
 // https://immersive-web.github.io/layers/#xrwebglsubimagetype
-[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+[SecureContext, Exposed=Window, Pref="dom_webxr_layers_enabled"]
 interface XRWebGLSubImage : XRSubImage {
   [SameObject] readonly attribute WebGLTexture colorTexture;
   [SameObject] readonly attribute WebGLTexture? depthStencilTexture;
diff --git a/components/script/dom/webxr/xrsystem.rs b/components/script/dom/webxr/xrsystem.rs
index 82736d540e9..f5f50ab93f1 100644
--- a/components/script/dom/webxr/xrsystem.rs
+++ b/components/script/dom/webxr/xrsystem.rs
@@ -168,7 +168,7 @@ impl XRSystemMethods<crate::DomTypeHolder> for XRSystem {
 
         if mode != XRSessionMode::Inline {
             if !ScriptThread::is_user_interacting() {
-                if pref!(dom.webxr.unsafe_assume_user_intent) {
+                if pref!(dom_webxr_unsafe_assume_user_intent) {
                     warn!("The dom.webxr.unsafe-assume-user-intent preference assumes user intent to enter WebXR.");
                 } else {
                     promise.reject_error(Error::Security);
@@ -232,7 +232,7 @@ impl XRSystemMethods<crate::DomTypeHolder> for XRSystem {
         let init = SessionInit {
             required_features,
             optional_features,
-            first_person_observer_view: pref!(dom.webxr.first_person_observer_view),
+            first_person_observer_view: pref!(dom_webxr_first_person_observer_view),
         };
 
         let mut trusted = Some(TrustedPromise::new(promise.clone()));
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index 2b79e923590..41fd03f3996 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -802,7 +802,7 @@ impl WindowMethods<crate::DomTypeHolder> for Window {
             // https://html.spec.whatwg.org/multipage/#script-closable
             let is_script_closable = (self.is_top_level() && history_length == 1) ||
                 is_auxiliary ||
-                pref!(dom.allow_scripts_to_close_windows);
+                pref!(dom_allow_scripts_to_close_windows);
 
             // TODO: rest of Step 3:
             // Is the incumbent settings object's responsible browsing context familiar with current?
diff --git a/components/script/init.rs b/components/script/init.rs
index 324714a3831..f2e88f6ea1a 100644
--- a/components/script/init.rs
+++ b/components/script/init.rs
@@ -62,7 +62,7 @@ unsafe extern "C" fn is_dom_object(obj: *mut JSObject) -> bool {
 #[allow(unsafe_code)]
 pub fn init() -> JSEngineSetup {
     unsafe {
-        if pref!(js.disable_jit) {
+        if pref!(js_disable_jit) {
             js::jsapi::DisableJitBackend();
         }
         proxyhandler::init();
diff --git a/components/script/script_runtime.rs b/components/script/script_runtime.rs
index 5f084685445..910e1ba0ef7 100644
--- a/components/script/script_runtime.rs
+++ b/components/script/script_runtime.rs
@@ -615,24 +615,24 @@ impl Runtime {
         JS_SetGlobalJitCompilerOption(
             cx,
             JSJitCompilerOption::JSJITCOMPILER_BASELINE_INTERPRETER_ENABLE,
-            pref!(js.baseline_interpreter.enabled) as u32,
+            pref!(js_baseline_interpreter_enabled) as u32,
         );
         JS_SetGlobalJitCompilerOption(
             cx,
             JSJitCompilerOption::JSJITCOMPILER_BASELINE_ENABLE,
-            pref!(js.baseline_jit.enabled) as u32,
+            pref!(js_baseline_jit_enabled) as u32,
         );
         JS_SetGlobalJitCompilerOption(
             cx,
             JSJitCompilerOption::JSJITCOMPILER_ION_ENABLE,
-            pref!(js.ion.enabled) as u32,
+            pref!(js_ion_enabled) as u32,
         );
-        cx_opts.compileOptions_.asmJSOption_ = if pref!(js.asmjs.enabled) {
+        cx_opts.compileOptions_.asmJSOption_ = if pref!(js_asmjs_enabled) {
             AsmJSOption::Enabled
         } else {
             AsmJSOption::DisabledByAsmJSPref
         };
-        let wasm_enabled = pref!(js.wasm.enabled);
+        let wasm_enabled = pref!(js_wasm_enabled);
         cx_opts.set_wasm_(wasm_enabled);
         if wasm_enabled {
             // If WASM is enabled without setting the buildIdOp,
@@ -640,20 +640,20 @@ impl Runtime {
             // https://dxr.mozilla.org/mozilla-central/source/js/src/wasm/WasmTypes.cpp#458
             SetProcessBuildIdOp(Some(servo_build_id));
         }
-        cx_opts.set_wasmBaseline_(pref!(js.wasm.baseline.enabled));
-        cx_opts.set_wasmIon_(pref!(js.wasm.ion.enabled));
+        cx_opts.set_wasmBaseline_(pref!(js_wasm_baseline_enabled));
+        cx_opts.set_wasmIon_(pref!(js_wasm_ion_enabled));
         // TODO: handle js.throw_on_asmjs_validation_failure (needs new Spidermonkey)
         JS_SetGlobalJitCompilerOption(
             cx,
             JSJitCompilerOption::JSJITCOMPILER_NATIVE_REGEXP_ENABLE,
-            pref!(js.native_regex.enabled) as u32,
+            pref!(js_native_regex_enabled) as u32,
         );
-        JS_SetParallelParsingEnabled(cx, pref!(js.parallel_parsing.enabled));
-        JS_SetOffthreadIonCompilationEnabled(cx, pref!(js.offthread_compilation.enabled));
+        JS_SetParallelParsingEnabled(cx, pref!(js_parallel_parsing_enabled));
+        JS_SetOffthreadIonCompilationEnabled(cx, pref!(js_offthread_compilation_enabled));
         JS_SetGlobalJitCompilerOption(
             cx,
             JSJitCompilerOption::JSJITCOMPILER_BASELINE_WARMUP_TRIGGER,
-            if pref!(js.baseline_jit.unsafe_eager_compilation.enabled) {
+            if pref!(js_baseline_jit_unsafe_eager_compilation_enabled) {
                 0
             } else {
                 u32::MAX
@@ -662,7 +662,7 @@ impl Runtime {
         JS_SetGlobalJitCompilerOption(
             cx,
             JSJitCompilerOption::JSJITCOMPILER_ION_NORMAL_WARMUP_TRIGGER,
-            if pref!(js.ion.unsafe_eager_compilation.enabled) {
+            if pref!(js_ion_unsafe_eager_compilation_enabled) {
                 0
             } else {
                 u32::MAX
@@ -676,7 +676,7 @@ impl Runtime {
         JS_SetGCParameter(
             cx,
             JSGCParamKey::JSGC_MAX_BYTES,
-            in_range(pref!(js.mem.max), 1, 0x100)
+            in_range(pref!(js_mem_max), 1, 0x100)
                 .map(|val| (val * 1024 * 1024) as u32)
                 .unwrap_or(u32::MAX),
         );
@@ -684,49 +684,49 @@ impl Runtime {
         JS_SetGCParameter(
             cx,
             JSGCParamKey::JSGC_INCREMENTAL_GC_ENABLED,
-            pref!(js.mem.gc.incremental.enabled) as u32,
+            pref!(js_mem_gc_incremental_enabled) as u32,
         );
         JS_SetGCParameter(
             cx,
             JSGCParamKey::JSGC_PER_ZONE_GC_ENABLED,
-            pref!(js.mem.gc.per_zone.enabled) as u32,
+            pref!(js_mem_gc_per_zone_enabled) as u32,
         );
-        if let Some(val) = in_range(pref!(js.mem.gc.incremental.slice_ms), 0, 100_000) {
+        if let Some(val) = in_range(pref!(js_mem_gc_incremental_slice_ms), 0, 100_000) {
             JS_SetGCParameter(cx, JSGCParamKey::JSGC_SLICE_TIME_BUDGET_MS, val as u32);
         }
         JS_SetGCParameter(
             cx,
             JSGCParamKey::JSGC_COMPACTING_ENABLED,
-            pref!(js.mem.gc.compacting.enabled) as u32,
+            pref!(js_mem_gc_compacting_enabled) as u32,
         );
 
-        if let Some(val) = in_range(pref!(js.mem.gc.high_frequency_time_limit_ms), 0, 10_000) {
+        if let Some(val) = in_range(pref!(js_mem_gc_high_frequency_time_limit_ms), 0, 10_000) {
             JS_SetGCParameter(cx, JSGCParamKey::JSGC_HIGH_FREQUENCY_TIME_LIMIT, val as u32);
         }
-        if let Some(val) = in_range(pref!(js.mem.gc.low_frequency_heap_growth), 0, 10_000) {
+        if let Some(val) = in_range(pref!(js_mem_gc_low_frequency_heap_growth), 0, 10_000) {
             JS_SetGCParameter(cx, JSGCParamKey::JSGC_LOW_FREQUENCY_HEAP_GROWTH, val as u32);
         }
-        if let Some(val) = in_range(pref!(js.mem.gc.high_frequency_heap_growth_min), 0, 10_000) {
+        if let Some(val) = in_range(pref!(js_mem_gc_high_frequency_heap_growth_min), 0, 10_000) {
             JS_SetGCParameter(
                 cx,
                 JSGCParamKey::JSGC_HIGH_FREQUENCY_LARGE_HEAP_GROWTH,
                 val as u32,
             );
         }
-        if let Some(val) = in_range(pref!(js.mem.gc.high_frequency_heap_growth_max), 0, 10_000) {
+        if let Some(val) = in_range(pref!(js_mem_gc_high_frequency_heap_growth_max), 0, 10_000) {
             JS_SetGCParameter(
                 cx,
                 JSGCParamKey::JSGC_HIGH_FREQUENCY_SMALL_HEAP_GROWTH,
                 val as u32,
             );
         }
-        if let Some(val) = in_range(pref!(js.mem.gc.high_frequency_low_limit_mb), 0, 10_000) {
+        if let Some(val) = in_range(pref!(js_mem_gc_high_frequency_low_limit_mb), 0, 10_000) {
             JS_SetGCParameter(cx, JSGCParamKey::JSGC_SMALL_HEAP_SIZE_MAX, val as u32);
         }
-        if let Some(val) = in_range(pref!(js.mem.gc.high_frequency_high_limit_mb), 0, 10_000) {
+        if let Some(val) = in_range(pref!(js_mem_gc_high_frequency_high_limit_mb), 0, 10_000) {
             JS_SetGCParameter(cx, JSGCParamKey::JSGC_LARGE_HEAP_SIZE_MIN, val as u32);
         }
-        /*if let Some(val) = in_range(pref!(js.mem.gc.allocation_threshold_factor), 0, 10_000) {
+        /*if let Some(val) = in_range(pref!(js_mem_gc_allocation_threshold_factor), 0, 10_000) {
             JS_SetGCParameter(cx, JSGCParamKey::JSGC_NON_INCREMENTAL_FACTOR, val as u32);
         }*/
         /*
@@ -736,10 +736,10 @@ impl Runtime {
             // JSGC_LARGE_HEAP_INCREMENTAL_LIMIT
             pref("javascript.options.mem.gc_large_heap_incremental_limit", 110);
         */
-        if let Some(val) = in_range(pref!(js.mem.gc.empty_chunk_count_min), 0, 10_000) {
+        if let Some(val) = in_range(pref!(js_mem_gc_empty_chunk_count_min), 0, 10_000) {
             JS_SetGCParameter(cx, JSGCParamKey::JSGC_MIN_EMPTY_CHUNK_COUNT, val as u32);
         }
-        if let Some(val) = in_range(pref!(js.mem.gc.empty_chunk_count_max), 0, 10_000) {
+        if let Some(val) = in_range(pref!(js_mem_gc_empty_chunk_count_max), 0, 10_000) {
             JS_SetGCParameter(cx, JSGCParamKey::JSGC_MAX_EMPTY_CHUNK_COUNT, val as u32);
         }
 
@@ -911,11 +911,11 @@ unsafe extern "C" fn servo_build_id(build_id: *mut BuildIdCharVector) -> bool {
 unsafe fn set_gc_zeal_options(cx: *mut RawJSContext) {
     use js::jsapi::SetGCZeal;
 
-    let level = match pref!(js.mem.gc.zeal.level) {
+    let level = match pref!(js_mem_gc_zeal_level) {
         level @ 0..=14 => level as u8,
         _ => return,
     };
-    let frequency = match pref!(js.mem.gc.zeal.frequency) {
+    let frequency = match pref!(js_mem_gc_zeal_frequency) {
         frequency if frequency >= 0 => frequency as u32,
         // https://searchfox.org/mozilla-esr128/source/js/public/GCAPI.h#1392
         _ => 5000,
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index a4704cb2b42..0cf14937c4c 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -2794,7 +2794,7 @@ impl ScriptThread {
         self.background_hang_monitor.unregister();
 
         // If we're in multiprocess mode, shut-down the IPC router for this process.
-        if opts::multiprocess() {
+        if opts::get().multiprocess {
             debug!("Exiting IPC router thread in script thread.");
             ROUTER.shutdown();
         }
diff --git a/components/script/serviceworker_manager.rs b/components/script/serviceworker_manager.rs
index 9f1ad777110..23723ca39df 100644
--- a/components/script/serviceworker_manager.rs
+++ b/components/script/serviceworker_manager.rs
@@ -517,5 +517,5 @@ impl ServiceWorkerManagerFactory for ServiceWorkerManager {
 }
 
 pub(crate) fn serviceworker_enabled() -> bool {
-    pref!(dom.serviceworker.enabled)
+    pref!(dom_serviceworker_enabled)
 }
diff --git a/components/script/timers.rs b/components/script/timers.rs
index 9999dac01d7..60b079ebcf8 100644
--- a/components/script/timers.rs
+++ b/components/script/timers.rs
@@ -237,7 +237,7 @@ impl OneshotTimers {
     }
 
     pub(crate) fn slow_down(&self) {
-        let min_duration_ms = pref!(js.timers.minimum_duration) as u64;
+        let min_duration_ms = pref!(js_timers_minimum_duration) as u64;
         self.js_timers
             .set_min_duration(Duration::from_millis(min_duration_ms));
     }
diff --git a/components/servo/lib.rs b/components/servo/lib.rs
index 93f51c318eb..d9b2e560fba 100644
--- a/components/servo/lib.rs
+++ b/components/servo/lib.rs
@@ -78,6 +78,8 @@ use profile_traits::{mem, time};
 use script::{JSEngineSetup, ServiceWorkerManager};
 use script_layout_interface::LayoutFactory;
 use script_traits::{ScriptToConstellationChan, WindowSizeData};
+use servo_config::opts::Opts;
+use servo_config::prefs::Preferences;
 use servo_config::{opts, pref, prefs};
 use servo_media::player::context::GlContext;
 use servo_media::ServoMedia;
@@ -232,6 +234,8 @@ where
     )]
     #[allow(clippy::new_ret_no_self)]
     pub fn new(
+        opts: Opts,
+        preferences: Preferences,
         rendering_context: RenderingContext,
         mut embedder: Box<dyn EmbedderMethods>,
         window: Rc<Window>,
@@ -239,8 +243,13 @@ where
         composite_target: CompositeTarget,
     ) -> Servo<Window> {
         // Global configuration options, parsed from the command line.
+        opts::set_options(opts);
         let opts = opts::get();
 
+        // Set the preferences globally.
+        // TODO: It would be better to make these private to a particular Servo instance.
+        servo_config::prefs::set(preferences);
+
         use std::sync::atomic::Ordering;
 
         style::context::DEFAULT_DISABLE_STYLE_SHARING_CACHE
@@ -309,9 +318,9 @@ where
         );
         let mem_profiler_chan = profile_mem::Profiler::create(opts.mem_profiler_period);
 
-        let devtools_sender = if opts.devtools_server_enabled {
+        let devtools_sender = if pref!(devtools_server_enabled) {
             Some(devtools::start_server(
-                opts.devtools_port,
+                pref!(devtools_server_port) as u16,
                 embedder_proxy.clone(),
             ))
         } else {
@@ -330,7 +339,7 @@ where
             );
 
             let render_notifier = Box::new(RenderNotifier::new(compositor_proxy.clone()));
-            let clear_color = servo_config::pref!(shell.background_color.rgba);
+            let clear_color = servo_config::pref!(shell_background_color_rgba);
             let clear_color = ColorF::new(
                 clear_color[0] as f32,
                 clear_color[1] as f32,
@@ -346,8 +355,8 @@ where
             };
             let worker_threads = thread::available_parallelism()
                 .map(|i| i.get())
-                .unwrap_or(pref!(threadpools.fallback_worker_num) as usize)
-                .min(pref!(threadpools.webrender_workers.max).max(1) as usize);
+                .unwrap_or(pref!(threadpools_fallback_worker_num) as usize)
+                .min(pref!(threadpools_webrender_workers_max).max(1) as usize);
             let workers = Some(Arc::new(
                 rayon::ThreadPoolBuilder::new()
                     .num_threads(worker_threads)
@@ -372,9 +381,9 @@ where
                     } else {
                         ShaderPrecacheFlags::empty()
                     },
-                    enable_subpixel_aa: pref!(gfx.subpixel_text_antialiasing.enabled) &&
+                    enable_subpixel_aa: pref!(gfx_subpixel_text_antialiasing_enabled) &&
                         !opts.debug.disable_subpixel_text_antialiasing,
-                    allow_texture_swizzling: pref!(gfx.texture_swizzling.enabled),
+                    allow_texture_swizzling: pref!(gfx_texture_swizzling_enabled),
                     clear_color,
                     upload_method,
                     workers,
@@ -427,7 +436,7 @@ where
             webxr::MainThreadRegistry::new(event_loop_waker, webxr_layer_grand_manager)
                 .expect("Failed to create WebXR device registry");
         #[cfg(feature = "webxr")]
-        if pref!(dom.webxr.enabled) {
+        if pref!(dom_webxr_enabled) {
             embedder.register_webxr(&mut webxr_main_thread, embedder_proxy.clone());
         }
 
@@ -587,7 +596,7 @@ where
         external_images: Arc<Mutex<WebrenderExternalImageRegistry>>,
         rendering_context: &RenderingContext,
     ) -> (WindowGLContext, Option<GLPlayerThreads>) {
-        if !pref!(media.glvideo.enabled) {
+        if !pref!(media_glvideo_enabled) {
             return (
                 WindowGLContext {
                     gl_context: GlContext::Unknown,
@@ -1192,7 +1201,7 @@ pub fn run_content_process(token: String) {
 
     let unprivileged_content = unprivileged_content_receiver.recv().unwrap();
     opts::set_options(unprivileged_content.opts());
-    prefs::add_user_prefs(unprivileged_content.prefs());
+    prefs::set(unprivileged_content.prefs().clone());
 
     // Enter the sandbox if necessary.
     if opts::get().sandbox {
diff --git a/components/shared/canvas/webgl.rs b/components/shared/canvas/webgl.rs
index 4fb5691fd58..8bd1d9cd440 100644
--- a/components/shared/canvas/webgl.rs
+++ b/components/shared/canvas/webgl.rs
@@ -33,7 +33,7 @@ pub fn webgl_channel<T>() -> Option<(WebGLSender<T>, WebGLReceiver<T>)>
 where
     T: for<'de> Deserialize<'de> + Serialize,
 {
-    base::generic_channel::channel(servo_config::opts::multiprocess())
+    base::generic_channel::channel(servo_config::opts::get().multiprocess)
 }
 
 /// Entry point channel type used for sending WebGLMsg messages to the WebGL renderer.
diff --git a/components/shared/embedder/resources.rs b/components/shared/embedder/resources.rs
index 9fdb8548135..a29abf5328b 100644
--- a/components/shared/embedder/resources.rs
+++ b/components/shared/embedder/resources.rs
@@ -55,9 +55,6 @@ pub fn sandbox_access_files_dirs() -> Vec<PathBuf> {
 }
 
 pub enum Resource {
-    /// A json file of `servo_config::pref_util::Preferences` configuration.
-    /// It can be empty but lots of features will be disabled.
-    Preferences,
     /// A list of GATT services that are blocked from being used by web bluetooth.
     /// The format of the file is a list of UUIDs, one per line, with an optional second word to specify the
     /// type of blocklist.
@@ -121,7 +118,6 @@ pub enum Resource {
 impl Resource {
     pub fn filename(&self) -> &'static str {
         match self {
-            Resource::Preferences => "prefs.json",
             Resource::BluetoothBlocklist => "gatt_blocklist.txt",
             Resource::DomainList => "public_domains.txt",
             Resource::HstsPreloadList => "hsts_preload.json",
@@ -164,7 +160,6 @@ fn resources_for_tests() -> Box<dyn ResourceReaderMethods + Sync + Send> {
         }
         fn read(&self, file: Resource) -> Vec<u8> {
             match file {
-                Resource::Preferences => &include_bytes!("../../../resources/prefs.json")[..],
                 Resource::BluetoothBlocklist => {
                     &include_bytes!("../../../resources/gatt_blocklist.txt")[..]
                 },
diff --git a/components/webdriver_server/lib.rs b/components/webdriver_server/lib.rs
index 74b0a0b8f23..c99cd726275 100644
--- a/components/webdriver_server/lib.rs
+++ b/components/webdriver_server/lib.rs
@@ -41,8 +41,7 @@ use serde::de::{Deserializer, MapAccess, Visitor};
 use serde::ser::Serializer;
 use serde::{Deserialize, Serialize};
 use serde_json::{json, Value};
-use servo_config::prefs;
-use servo_config::prefs::PrefValue;
+use servo_config::prefs::{self, PrefValue, Preferences};
 use servo_url::ServoUrl;
 use style_traits::CSSPixel;
 use uuid::Uuid;
@@ -295,7 +294,6 @@ impl Serialize for WebDriverPrefValue {
             PrefValue::Str(ref s) => serializer.serialize_str(s),
             PrefValue::Float(f) => serializer.serialize_f64(f),
             PrefValue::Int(i) => serializer.serialize_i64(i),
-            PrefValue::Missing => serializer.serialize_unit(),
             PrefValue::Array(ref v) => v
                 .iter()
                 .map(|value| WebDriverPrefValue(value.clone()))
@@ -1759,7 +1757,7 @@ impl Handler {
             .map(|item| {
                 (
                     item.clone(),
-                    serde_json::to_value(prefs::pref_map().get(item)).unwrap(),
+                    serde_json::to_value(prefs::get().get_value(item)).unwrap(),
                 )
             })
             .collect::<BTreeMap<_, _>>();
@@ -1773,12 +1771,12 @@ impl Handler {
         &self,
         parameters: &SetPrefsParameters,
     ) -> WebDriverResult<WebDriverResponse> {
+        let mut current_preferences = prefs::get().clone();
         for (key, value) in parameters.prefs.iter() {
-            prefs::set_stylo_pref(key, value.0.clone());
-            prefs::pref_map()
-                .set(key, value.0.clone())
-                .expect("Failed to set preference");
+            current_preferences.set_value(key, value.0.clone());
         }
+        prefs::set(current_preferences);
+
         Ok(WebDriverResponse::Void)
     }
 
@@ -1786,27 +1784,29 @@ impl Handler {
         &self,
         parameters: &GetPrefsParameters,
     ) -> WebDriverResult<WebDriverResponse> {
-        let prefs = if parameters.prefs.is_empty() {
-            //TODO: support resetting stylo preferences
-            prefs::pref_map().reset_all();
-            BTreeMap::new()
+        let (new_preferences, map) = if parameters.prefs.is_empty() {
+            (Preferences::default(), BTreeMap::new())
         } else {
-            parameters
+            // If we only want to reset some of the preferences.
+            let mut new_preferences = prefs::get().clone();
+            let default_preferences = Preferences::default();
+            for key in parameters.prefs.iter() {
+                new_preferences.set_value(key, default_preferences.get_value(key))
+            }
+
+            let map = parameters
                 .prefs
                 .iter()
-                .map(|item| {
-                    (
-                        item.clone(),
-                        serde_json::to_value(
-                            prefs::pref_map().reset(item).unwrap_or(PrefValue::Missing),
-                        )
-                        .unwrap(),
-                    )
-                })
-                .collect::<BTreeMap<_, _>>()
+                .map(|item| (item.clone(), new_preferences.get_value(item)))
+                .collect::<BTreeMap<_, _>>();
+
+            (new_preferences, map)
         };
+
+        prefs::set(new_preferences);
+
         Ok(WebDriverResponse::Generic(ValueResponse(
-            serde_json::to_value(prefs)?,
+            serde_json::to_value(map)?,
         )))
     }
 }
diff --git a/components/webgpu/lib.rs b/components/webgpu/lib.rs
index 7d953d0ca6c..f67c55ab02e 100644
--- a/components/webgpu/lib.rs
+++ b/components/webgpu/lib.rs
@@ -44,7 +44,7 @@ impl WebGPU {
         external_images: Arc<Mutex<WebrenderExternalImageRegistry>>,
         wgpu_image_map: WGPUImageMap,
     ) -> Option<(Self, IpcReceiver<WebGPUMsg>)> {
-        if !pref!(dom.webgpu.enabled) {
+        if !pref!(dom_webgpu_enabled) {
             return None;
         }
         let (sender, receiver) = match ipc::channel() {
diff --git a/components/webgpu/wgpu_thread.rs b/components/webgpu/wgpu_thread.rs
index b2aa784754a..374fe2e8265 100644
--- a/components/webgpu/wgpu_thread.rs
+++ b/components/webgpu/wgpu_thread.rs
@@ -127,7 +127,7 @@ impl WGPU {
         external_images: Arc<Mutex<WebrenderExternalImageRegistry>>,
         wgpu_image_map: WGPUImageMap,
     ) -> Self {
-        let backend_pref = pref!(dom.webgpu.wgpu_backend);
+        let backend_pref = pref!(dom_webgpu_wgpu_backend);
         let backends = if backend_pref.is_empty() {
             wgt::Backends::PRIMARY
         } else {
diff --git a/ports/servoshell/Cargo.toml b/ports/servoshell/Cargo.toml
index af50b5ebc6f..835c854ecfd 100644
--- a/ports/servoshell/Cargo.toml
+++ b/ports/servoshell/Cargo.toml
@@ -56,6 +56,7 @@ webxr = ["dep:webxr", "libservo/webxr"]
 webgpu = ["libservo/webgpu"]
 
 [dependencies]
+euclid = { workspace = true }
 libc = { workspace = true }
 libservo = { path = "../../components/servo" }
 cfg-if = { workspace = true }
@@ -104,10 +105,10 @@ webxr = { workspace = true, optional = true }
 # For optional feature servo_allocator/use-system-allocator
 servo_allocator = { path = "../../components/allocator" }
 arboard = { version = "3" }
+dirs = "5.0"
 egui = { version = "0.30.0" }
 egui_glow = { version = "0.30.0", features = ["winit"] }
 egui-winit = { version = "0.30.0", default-features = false, features = ["clipboard", "wayland"] }
-euclid = { workspace = true }
 gilrs = "0.11.0"
 gleam = { workspace = true }
 glow = "0.16.0"
@@ -116,6 +117,7 @@ http = { workspace = true }
 net = { path = "../../components/net" }
 net_traits = { workspace = true }
 raw-window-handle = "0.6"
+serde_json = { workspace = true }
 shellwords = "1.0.0"
 surfman = { workspace = true, features = ["sm-x11", "sm-raw-window-handle-06"] }
 tinyfiledialogs = "3.0"
diff --git a/ports/servoshell/desktop/app.rs b/ports/servoshell/desktop/app.rs
index b65d495ee50..8014b48cba3 100644
--- a/ports/servoshell/desktop/app.rs
+++ b/ports/servoshell/desktop/app.rs
@@ -15,7 +15,8 @@ use raw_window_handle::HasDisplayHandle;
 use servo::base::id::WebViewId;
 use servo::compositing::windowing::EmbedderEvent;
 use servo::compositing::CompositeTarget;
-use servo::config::opts;
+use servo::config::opts::Opts;
+use servo::config::prefs::Preferences;
 use servo::embedder_traits::EventLoopWaker;
 use servo::servo_config::pref;
 use servo::url::ServoUrl;
@@ -38,21 +39,22 @@ use crate::desktop::embedder::{EmbedderCallbacks, XrDiscovery};
 use crate::desktop::tracing::trace_winit_event;
 use crate::desktop::window_trait::WindowPortsMethods;
 use crate::parser::get_default_url;
+use crate::prefs::ServoShellPreferences;
 
 pub struct App {
+    opts: Opts,
+    preferences: Preferences,
+    servo_shell_preferences: ServoShellPreferences,
     servo: Option<Servo<dyn WindowPortsMethods>>,
     webviews: Option<WebViewManager<dyn WindowPortsMethods>>,
     event_queue: Vec<EmbedderEvent>,
     suspended: Cell<bool>,
     windows: HashMap<WindowId, Rc<dyn WindowPortsMethods>>,
     minibrowser: Option<Minibrowser>,
-    user_agent: Option<String>,
     waker: Box<dyn EventLoopWaker>,
     initial_url: ServoUrl,
     t_start: Instant,
     t: Instant,
-    do_not_use_native_titlebar: bool,
-    device_pixel_ratio_override: Option<f32>,
 }
 
 enum Present {
@@ -73,38 +75,40 @@ enum PumpResult {
 
 impl App {
     pub fn new(
+        opts: Opts,
+        preferences: Preferences,
+        servo_shell_preferences: ServoShellPreferences,
         events_loop: &EventsLoop,
-        user_agent: Option<String>,
-        url: Option<String>,
-        do_not_use_native_titlebar: bool,
-        device_pixel_ratio_override: Option<f32>,
     ) -> Self {
-        // Handle browser state.
-        let initial_url = get_default_url(url.as_deref(), env::current_dir().unwrap(), |path| {
-            fs::metadata(path).is_ok()
-        });
+        let initial_url = get_default_url(
+            servo_shell_preferences.url.as_deref(),
+            env::current_dir().unwrap(),
+            |path| fs::metadata(path).is_ok(),
+            &servo_shell_preferences,
+        );
+
         let t = Instant::now();
         App {
+            opts,
+            preferences,
+            servo_shell_preferences,
             event_queue: vec![],
             webviews: None,
             servo: None,
             suspended: Cell::new(false),
             windows: HashMap::new(),
             minibrowser: None,
-            user_agent,
             waker: events_loop.create_event_loop_waker(),
             initial_url: initial_url.clone(),
             t_start: t,
             t,
-            do_not_use_native_titlebar,
-            device_pixel_ratio_override,
         }
     }
 
     /// Initialize Application once event loop start running.
     pub fn init(&mut self, event_loop: Option<&ActiveEventLoop>) {
         // Create rendering context
-        let rendering_context = if opts::get().headless {
+        let rendering_context = if self.opts.headless {
             let connection = Connection::new().expect("Failed to create connection");
             let adapter = connection
                 .create_software_adapter()
@@ -112,7 +116,7 @@ impl App {
             RenderingContext::create(
                 &connection,
                 &adapter,
-                Some(opts::get().initial_window_size.to_untyped().to_i32()),
+                Some(self.opts.initial_window_size.to_untyped().to_i32()),
             )
             .expect("Failed to create WR surfman")
         } else {
@@ -129,18 +133,20 @@ impl App {
                 .expect("Failed to create WR surfman")
         };
 
-        let window = if opts::get().headless {
+        let window = if self.opts.headless {
             headless_window::Window::new(
-                opts::get().initial_window_size,
-                self.device_pixel_ratio_override,
+                self.opts.initial_window_size,
+                self.servo_shell_preferences.device_pixel_ratio_override,
+                self.opts.screen_size_override,
             )
         } else {
             Rc::new(headed_window::Window::new(
+                &self.opts,
                 &rendering_context,
-                opts::get().initial_window_size,
+                self.opts.initial_window_size,
                 event_loop.unwrap(),
-                self.do_not_use_native_titlebar,
-                self.device_pixel_ratio_override,
+                self.servo_shell_preferences.no_native_titlebar,
+                self.servo_shell_preferences.device_pixel_ratio_override,
             ))
         };
 
@@ -171,7 +177,7 @@ impl App {
         self.event_queue.push(EmbedderEvent::Idle);
         let (_, window) = self.windows.iter().next().unwrap();
 
-        let xr_discovery = if pref!(dom.webxr.openxr.enabled) && !opts::get().headless {
+        let xr_discovery = if pref!(dom_webxr_openxr_enabled) && !self.opts.headless {
             #[cfg(target_os = "windows")]
             let openxr = {
                 let app_info = AppInfo::new("Servoshell", 0, "Servo", 0);
@@ -181,7 +187,7 @@ impl App {
             let openxr = None;
 
             openxr
-        } else if pref!(dom.webxr.glwindow.enabled) && !opts::get().headless {
+        } else if pref!(dom_webxr_glwindow_enabled) && !self.opts.headless {
             let window = window.new_glwindow(event_loop.unwrap());
             Some(XrDiscovery::GlWindow(GlWindowDiscovery::new(window)))
         } else {
@@ -198,10 +204,12 @@ impl App {
             CompositeTarget::Window
         };
         let mut servo = Servo::new(
+            self.opts.clone(),
+            self.preferences.clone(),
             rendering_context,
             embedder,
             window.clone(),
-            self.user_agent.clone(),
+            self.servo_shell_preferences.user_agent.clone(),
             composite_target,
         );
 
@@ -243,7 +251,7 @@ impl App {
 
         // If the Gamepad API is enabled, handle gamepad events from GilRs.
         // Checking for focused_webview_id should ensure we'll have a valid browsing context.
-        if pref!(dom.gamepad.enabled) && webviews.focused_webview_id().is_some() {
+        if pref!(dom_gamepad_enabled) && webviews.focused_webview_id().is_some() {
             webviews.handle_gamepad_events();
         }
 
@@ -254,7 +262,7 @@ impl App {
         let mut need_update = false;
         loop {
             // Consume and handle those embedder messages.
-            let servo_event_response = webviews.handle_servo_events(embedder_messages);
+            let servo_event_response = webviews.handle_servo_events(&self.opts, embedder_messages);
             need_present |= servo_event_response.need_present;
             need_update |= servo_event_response.need_update;
 
@@ -524,7 +532,11 @@ impl ApplicationHandler<WakerEvent> for App {
         if let Some(ref minibrowser) = self.minibrowser {
             let webviews = &mut self.webviews.as_mut().unwrap();
             let app_event_queue = &mut self.event_queue;
-            minibrowser.queue_embedder_events_for_minibrowser_events(webviews, app_event_queue);
+            minibrowser.queue_embedder_events_for_minibrowser_events(
+                webviews,
+                app_event_queue,
+                &self.servo_shell_preferences,
+            );
         }
 
         self.handle_events_with_winit(event_loop, window);
@@ -565,7 +577,11 @@ impl ApplicationHandler<WakerEvent> for App {
         if let Some(ref minibrowser) = self.minibrowser {
             let webviews = &mut self.webviews.as_mut().unwrap();
             let app_event_queue = &mut self.event_queue;
-            minibrowser.queue_embedder_events_for_minibrowser_events(webviews, app_event_queue);
+            minibrowser.queue_embedder_events_for_minibrowser_events(
+                webviews,
+                app_event_queue,
+                &self.servo_shell_preferences,
+            );
         }
 
         self.handle_events_with_winit(event_loop, window);
diff --git a/ports/servoshell/desktop/cli.rs b/ports/servoshell/desktop/cli.rs
index ff9315a4bb9..1241e4e2af3 100644
--- a/ports/servoshell/desktop/cli.rs
+++ b/ports/servoshell/desktop/cli.rs
@@ -2,16 +2,12 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use std::{env, panic, process};
-
-use getopts::Options;
-use log::error;
-use servo::config::opts::{self, ArgumentParsingResult};
-use servo::servo_config::pref;
+use std::{env, panic};
 
 use crate::desktop::app::App;
 use crate::desktop::events_loop::EventsLoop;
 use crate::panic_hook;
+use crate::prefs::{parse_command_line_arguments, ArgumentParsingResult};
 
 pub fn main() {
     crate::crash_handler::install();
@@ -19,98 +15,23 @@ pub fn main() {
     crate::init_crypto();
     crate::resources::init();
 
-    // Parse the command line options and store them globally
-    let args: Vec<String> = env::args().collect();
-    let mut opts = Options::new();
-    opts.optflag(
-        "",
-        "clean-shutdown",
-        "Do not shutdown until all threads have finished (macos only)",
-    );
-    opts.optflag("b", "no-native-titlebar", "Do not use native titlebar");
-    opts.optopt("", "device-pixel-ratio", "Device pixels per px", "");
-    opts.optopt(
-        "u",
-        "user-agent",
-        "Set custom user agent string (or ios / android / desktop for platform default)",
-        "NCSA Mosaic/1.0 (X11;SunOS 4.1.4 sun4m)",
-    );
-    opts.optmulti(
-        "",
-        "pref",
-        "A preference to set to enable",
-        "dom.bluetooth.enabled",
-    );
-    opts.optmulti(
-        "",
-        "pref",
-        "A preference to set to disable",
-        "dom.webgpu.enabled=false",
-    );
-    opts.optmulti(
-        "",
-        "prefs-file",
-        "Load in additional prefs from a file.",
-        "--prefs-file /path/to/prefs.json",
-    );
-
-    let opts_matches;
-    let content_process_token;
-
-    match opts::from_cmdline_args(opts, &args) {
-        ArgumentParsingResult::ContentProcess(matches, token) => {
-            opts_matches = matches;
-            content_process_token = Some(token);
-        },
-        ArgumentParsingResult::ChromeProcess(matches) => {
-            opts_matches = matches;
-            content_process_token = None;
-        },
-    };
-
-    crate::prefs::register_user_prefs(&opts_matches);
-
     // TODO: once log-panics is released, can this be replaced by
     // log_panics::init()?
     panic::set_hook(Box::new(panic_hook::panic_hook));
 
-    if let Some(token) = content_process_token {
-        return servo::run_content_process(token);
-    }
-
-    if opts::get().is_printing_version {
-        println!("{}", crate::servo_version());
-        process::exit(0);
-    }
-
-    let clean_shutdown = opts_matches.opt_present("clean-shutdown");
-    let do_not_use_native_titlebar =
-        opts_matches.opt_present("no-native-titlebar") || !(pref!(shell.native_titlebar.enabled));
-    let device_pixel_ratio_override = opts_matches.opt_str("device-pixel-ratio").map(|dppx_str| {
-        dppx_str.parse().unwrap_or_else(|err| {
-            error!("Error parsing option: --device-pixel-ratio ({})", err);
-            process::exit(1);
-        })
-    });
-
-    let user_agent = opts_matches.opt_str("u");
-
-    let url_opt = if !opts_matches.free.is_empty() {
-        Some(&opts_matches.free[0][..])
-    } else {
-        None
+    let args = env::args().collect();
+    let (opts, preferences, servoshell_preferences) = match parse_command_line_arguments(args) {
+        ArgumentParsingResult::ContentProcess(token) => return servo::run_content_process(token),
+        ArgumentParsingResult::ChromeProcess(opts, preferences, servoshell_preferences) => {
+            (opts, preferences, servoshell_preferences)
+        },
     };
 
-    let event_loop = EventsLoop::new(opts::get().headless, opts::get().output_file.is_some())
+    let clean_shutdown = servoshell_preferences.clean_shutdown;
+    let event_loop = EventsLoop::new(opts.headless, opts.output_file.is_some())
         .expect("Failed to create events loop");
 
-    let mut app = App::new(
-        &event_loop,
-        user_agent,
-        url_opt.map(|s| s.to_string()),
-        do_not_use_native_titlebar,
-        device_pixel_ratio_override,
-    );
+    let mut app = App::new(opts, preferences, servoshell_preferences, &event_loop);
 
     event_loop.run_app(&mut app);
 
diff --git a/ports/servoshell/desktop/embedder.rs b/ports/servoshell/desktop/embedder.rs
index 16164ac199a..7d4d7d4a47d 100644
--- a/ports/servoshell/desktop/embedder.rs
+++ b/ports/servoshell/desktop/embedder.rs
@@ -48,7 +48,7 @@ impl EmbedderMethods for EmbedderCallbacks {
         xr: &mut webxr::MainThreadRegistry,
         _embedder_proxy: EmbedderProxy,
     ) {
-        if pref!(dom.webxr.test) {
+        if pref!(dom_webxr_test) {
             xr.register_mock(webxr::headless::HeadlessMockDiscovery::new());
         } else if let Some(xr_discovery) = self.xr_discovery.take() {
             match xr_discovery {
diff --git a/ports/servoshell/desktop/events_loop.rs b/ports/servoshell/desktop/events_loop.rs
index 7dc7b803f56..1ebaf42dc67 100644
--- a/ports/servoshell/desktop/events_loop.rs
+++ b/ports/servoshell/desktop/events_loop.rs
@@ -8,7 +8,6 @@ use std::sync::{Arc, Condvar, Mutex};
 use std::time;
 
 use log::warn;
-use servo::config::{pref, set_pref};
 use servo::embedder_traits::EventLoopWaker;
 use winit::error::EventLoopError;
 use winit::event_loop::EventLoop as WinitEventLoop;
@@ -90,10 +89,6 @@ impl EventsLoop {
             },
             EventLoop::Headless(ref data) => {
                 let (flag, condvar) = &**data;
-                if pref!(media.glvideo.enabled) {
-                    warn!("GL video rendering is not supported on headless windows.");
-                    set_pref!(media.glvideo.enabled, false);
-                }
 
                 app.init(None);
                 loop {
diff --git a/ports/servoshell/desktop/headed_window.rs b/ports/servoshell/desktop/headed_window.rs
index 14f322d67a5..e0214997c2f 100644
--- a/ports/servoshell/desktop/headed_window.rs
+++ b/ports/servoshell/desktop/headed_window.rs
@@ -14,10 +14,11 @@ use raw_window_handle::{HasDisplayHandle, HasWindowHandle};
 use servo::compositing::windowing::{
     AnimationState, EmbedderCoordinates, EmbedderEvent, MouseWindowEvent, WindowMethods,
 };
+use servo::config::opts::Opts;
 use servo::embedder_traits::Cursor;
 use servo::keyboard_types::{Key, KeyState, KeyboardEvent};
 use servo::script_traits::{TouchEventType, WheelDelta, WheelMode};
-use servo::servo_config::{opts, pref};
+use servo::servo_config::pref;
 use servo::servo_geometry::DeviceIndependentPixel;
 use servo::webrender_api::units::{DeviceIntPoint, DeviceIntRect, DeviceIntSize, DevicePixel};
 use servo::webrender_api::ScrollLocation;
@@ -57,14 +58,13 @@ pub struct Window {
 
 impl Window {
     pub fn new(
+        opts: &Opts,
         rendering_context: &RenderingContext,
         window_size: Size2D<u32, DeviceIndependentPixel>,
         event_loop: &ActiveEventLoop,
         no_native_titlebar: bool,
         device_pixel_ratio_override: Option<f32>,
     ) -> Window {
-        let opts = opts::get();
-
         // If there's no chrome, start off with the window invisible. It will be set to visible in
         // `load_end()`. This avoids an ugly flash of unstyled content (especially important since
         // unstyled content is white and chrome often has a transparent background). See issue
@@ -625,13 +625,13 @@ impl webxr::glwindow::GlWindow for XRWindow {
     }
 
     fn get_mode(&self) -> webxr::glwindow::GlWindowMode {
-        if pref!(dom.webxr.glwindow.red_cyan) {
+        if pref!(dom_webxr_glwindow_red_cyan) {
             webxr::glwindow::GlWindowMode::StereoRedCyan
-        } else if pref!(dom.webxr.glwindow.left_right) {
+        } else if pref!(dom_webxr_glwindow_left_right) {
             webxr::glwindow::GlWindowMode::StereoLeftRight
-        } else if pref!(dom.webxr.glwindow.spherical) {
+        } else if pref!(dom_webxr_glwindow_spherical) {
             webxr::glwindow::GlWindowMode::Spherical
-        } else if pref!(dom.webxr.glwindow.cubemap) {
+        } else if pref!(dom_webxr_glwindow_cubemap) {
             webxr::glwindow::GlWindowMode::Cubemap
         } else {
             webxr::glwindow::GlWindowMode::Blit
diff --git a/ports/servoshell/desktop/headless_window.rs b/ports/servoshell/desktop/headless_window.rs
index cb9aecb909d..06dbaa5983b 100644
--- a/ports/servoshell/desktop/headless_window.rs
+++ b/ports/servoshell/desktop/headless_window.rs
@@ -13,7 +13,6 @@ use euclid::{Box2D, Length, Point2D, Scale, Size2D};
 use servo::compositing::windowing::{
     AnimationState, EmbedderCoordinates, EmbedderEvent, WindowMethods,
 };
-use servo::config::opts;
 use servo::servo_geometry::DeviceIndependentPixel;
 use servo::webrender_api::units::{DeviceIntSize, DevicePixel};
 
@@ -34,6 +33,7 @@ impl Window {
     pub fn new(
         size: Size2D<u32, DeviceIndependentPixel>,
         device_pixel_ratio_override: Option<f32>,
+        screen_size_override: Option<Size2D<u32, DeviceIndependentPixel>>,
     ) -> Rc<dyn WindowPortsMethods> {
         let device_pixel_ratio_override: Option<Scale<f32, DeviceIndependentPixel, DevicePixel>> =
             device_pixel_ratio_override.map(Scale::new);
@@ -43,7 +43,7 @@ impl Window {
         let inner_size = Cell::new((size.to_f32() * hidpi_factor).to_i32());
         let window_rect = Box2D::from_origin_and_size(Point2D::zero(), size);
 
-        let screen_size = opts::get().screen_size_override.map_or_else(
+        let screen_size = screen_size_override.map_or_else(
             || window_rect.size(),
             |screen_size_override| screen_size_override.to_i32(),
         );
diff --git a/ports/servoshell/desktop/minibrowser.rs b/ports/servoshell/desktop/minibrowser.rs
index 51bfbb76ecc..8d4345a27a1 100644
--- a/ports/servoshell/desktop/minibrowser.rs
+++ b/ports/servoshell/desktop/minibrowser.rs
@@ -36,6 +36,7 @@ use super::geometry::winit_position_to_euclid_point;
 use super::webview::{LoadStatus, WebViewManager};
 use super::window_trait::WindowPortsMethods;
 use crate::parser::location_bar_input_to_url;
+use crate::prefs::ServoShellPreferences;
 
 pub struct Minibrowser {
     pub context: EguiGlow,
@@ -497,18 +498,20 @@ impl Minibrowser {
         &self,
         browser: &WebViewManager<dyn WindowPortsMethods>,
         app_event_queue: &mut Vec<EmbedderEvent>,
+        preferences: &ServoShellPreferences,
     ) {
         for event in self.event_queue.borrow_mut().drain(..) {
             let browser_id = browser.focused_webview_id().unwrap();
             match event {
                 MinibrowserEvent::Go => {
                     let location = self.location.borrow();
-                    if let Some(url) = location_bar_input_to_url(&location.clone()) {
-                        app_event_queue.push(EmbedderEvent::LoadUrl(browser_id, url));
-                    } else {
+                    let Some(url) =
+                        location_bar_input_to_url(&location.clone(), &preferences.searchpage)
+                    else {
                         warn!("failed to parse location");
                         break;
-                    }
+                    };
+                    app_event_queue.push(EmbedderEvent::LoadUrl(browser_id, url));
                 },
                 MinibrowserEvent::Back => {
                     app_event_queue.push(EmbedderEvent::Navigation(
diff --git a/ports/servoshell/desktop/webview.rs b/ports/servoshell/desktop/webview.rs
index 43e4007d77d..8a08ac2ec45 100644
--- a/ports/servoshell/desktop/webview.rs
+++ b/ports/servoshell/desktop/webview.rs
@@ -19,6 +19,7 @@ use keyboard_types::{Key, KeyboardEvent, Modifiers, ShortcutMatcher};
 use log::{debug, error, info, trace, warn};
 use servo::base::id::TopLevelBrowsingContextId as WebViewId;
 use servo::compositing::windowing::{EmbedderEvent, WebRenderDebugOption};
+use servo::config::opts::Opts;
 use servo::embedder_traits::{
     CompositorEventVariant, ContextMenuResult, DualRumbleEffectParams, EmbedderMsg, FilterPattern,
     GamepadHapticEffectType, PermissionPrompt, PermissionRequest, PromptCredentialsInput,
@@ -29,7 +30,6 @@ use servo::script_traits::{
     GamepadEvent, GamepadIndex, GamepadInputBounds, GamepadSupportedHapticEffects,
     GamepadUpdateType, TouchEventType, TraversalDirection,
 };
-use servo::servo_config::opts;
 use servo::servo_url::ServoUrl;
 use servo::webrender_api::units::DeviceRect;
 use servo::webrender_api::ScrollLocation;
@@ -630,6 +630,7 @@ where
     /// Returns true if the caller needs to manually present a new frame.
     pub fn handle_servo_events(
         &mut self,
+        opts: &Opts,
         events: Drain<'_, (Option<WebViewId>, EmbedderMsg)>,
     ) -> ServoEventResponse {
         let mut need_present = self.load_status() != LoadStatus::LoadComplete;
@@ -685,7 +686,7 @@ where
                     self.window.request_inner_size(size);
                 },
                 EmbedderMsg::Prompt(definition, origin) => {
-                    let res = if opts::get().headless {
+                    let res = if opts.headless {
                         match definition {
                             PromptDefinition::Alert(_message, sender) => sender.send(()),
                             PromptDefinition::YesNo(_message, sender) => {
@@ -927,10 +928,7 @@ where
                     };
                 },
                 EmbedderMsg::SelectFiles(patterns, multiple_files, sender) => {
-                    let res = match (
-                        opts::get().headless,
-                        get_selected_files(patterns, multiple_files),
-                    ) {
+                    let res = match (opts.headless, get_selected_files(patterns, multiple_files)) {
                         (true, _) | (false, None) => sender.send(None),
                         (false, Some(files)) => sender.send(Some(files)),
                     };
@@ -941,8 +939,10 @@ where
                     };
                 },
                 EmbedderMsg::PromptPermission(prompt, sender) => {
-                    let permission_state = prompt_user(prompt);
-                    let _ = sender.send(permission_state);
+                    let _ = sender.send(match opts.headless {
+                        true => PermissionRequest::Denied,
+                        false => prompt_user(prompt),
+                    });
                 },
                 EmbedderMsg::ShowIME(_kind, _text, _multiline, _rect) => {
                     debug!("ShowIME received");
@@ -1007,10 +1007,6 @@ where
 
 #[cfg(target_os = "linux")]
 fn prompt_user(prompt: PermissionPrompt) -> PermissionRequest {
-    if opts::get().headless {
-        return PermissionRequest::Denied;
-    }
-
     let message = match prompt {
         PermissionPrompt::Request(permission_name) => {
             format!("Do you want to grant permission for {:?}?", permission_name)
diff --git a/ports/servoshell/desktop/window_trait.rs b/ports/servoshell/desktop/window_trait.rs
index 030fa112056..356230feeb3 100644
--- a/ports/servoshell/desktop/window_trait.rs
+++ b/ports/servoshell/desktop/window_trait.rs
@@ -9,7 +9,6 @@ use std::rc::Rc;
 
 use euclid::{Length, Scale};
 use servo::compositing::windowing::{EmbedderEvent, WindowMethods};
-use servo::config::opts;
 use servo::embedder_traits::Cursor;
 use servo::servo_geometry::DeviceIndependentPixel;
 use servo::webrender_api::units::{DeviceIntPoint, DeviceIntSize, DevicePixel};
@@ -22,10 +21,7 @@ pub trait WindowPortsMethods: WindowMethods {
     fn id(&self) -> winit::window::WindowId;
     fn hidpi_factor(&self) -> Scale<f32, DeviceIndependentPixel, DevicePixel> {
         self.device_pixel_ratio_override()
-            .unwrap_or_else(|| match opts::get().output_file {
-                Some(_) => Scale::new(1.0),
-                None => self.device_hidpi_factor(),
-            })
+            .unwrap_or_else(|| self.device_hidpi_factor())
     }
     fn device_hidpi_factor(&self) -> Scale<f32, DeviceIndependentPixel, DevicePixel>;
     fn device_pixel_ratio_override(
diff --git a/ports/servoshell/egl/android.rs b/ports/servoshell/egl/android.rs
index 02eb9640e18..8845e43af85 100644
--- a/ports/servoshell/egl/android.rs
+++ b/ports/servoshell/egl/android.rs
@@ -7,7 +7,6 @@
 mod resources;
 mod simpleservo;
 
-use std::collections::HashMap;
 use std::os::raw::{c_char, c_int, c_void};
 use std::sync::Arc;
 
@@ -830,17 +829,6 @@ fn get_options<'local>(
     let native_window =
         unsafe { ANativeWindow_fromSurface(env.get_native_interface(), surface.as_raw()) };
 
-    // FIXME: enable JIT compilation on 32-bit Android after the startup crash issue (#31134) is fixed.
-    let prefs = if cfg!(target_pointer_width = "32") {
-        let mut prefs = HashMap::new();
-        prefs.insert("js.baseline_interpreter.enabled".to_string(), false.into());
-        prefs.insert("js.baseline_jit.enabled".to_string(), false.into());
-        prefs.insert("js.ion.enabled".to_string(), false.into());
-        Some(prefs)
-    } else {
-        None
-    };
-
     let opts = InitOptions {
         args: args.unwrap_or(vec![]),
         url,
@@ -848,7 +836,6 @@ fn get_options<'local>(
         density,
         xr_discovery: None,
         surfman_integration: simpleservo::SurfmanIntegration::Widget(native_window),
-        prefs,
     };
 
     Ok((opts, log, log_str, gst_debug_str))
diff --git a/ports/servoshell/egl/android/resources.rs b/ports/servoshell/egl/android/resources.rs
index fb9d837aeb6..227d97742a6 100644
--- a/ports/servoshell/egl/android/resources.rs
+++ b/ports/servoshell/egl/android/resources.rs
@@ -16,7 +16,6 @@ impl ResourceReaderInstance {
 impl ResourceReaderMethods for ResourceReaderInstance {
     fn read(&self, res: Resource) -> Vec<u8> {
         Vec::from(match res {
-            Resource::Preferences => &include_bytes!("../../../../resources/prefs.json")[..],
             Resource::HstsPreloadList => {
                 &include_bytes!("../../../../resources/hsts_preload.json")[..]
             },
diff --git a/ports/servoshell/egl/android/simpleservo.rs b/ports/servoshell/egl/android/simpleservo.rs
index 4d249e844d1..2e0b4786a11 100644
--- a/ports/servoshell/egl/android/simpleservo.rs
+++ b/ports/servoshell/egl/android/simpleservo.rs
@@ -3,23 +3,19 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use std::cell::RefCell;
-use std::collections::HashMap;
 use std::mem;
 use std::os::raw::c_void;
 use std::rc::Rc;
 
-use getopts::Options;
 use servo::base::id::WebViewId;
 use servo::compositing::windowing::EmbedderEvent;
 use servo::compositing::CompositeTarget;
-pub use servo::config::prefs::{add_user_prefs, PrefValue};
 use servo::embedder_traits::resources;
 /// The EventLoopWaker::wake function will be called from any thread.
 /// It will be called to notify embedder that some events are available,
 /// and that perform_updates need to be called
 pub use servo::embedder_traits::EventLoopWaker;
 pub use servo::embedder_traits::{InputMethodType, MediaSessionPlaybackState, PromptResult};
-use servo::servo_config::{opts, pref};
 use servo::servo_url::ServoUrl;
 pub use servo::webrender_api::units::DeviceIntRect;
 use servo::webrender_traits::RenderingContext;
@@ -31,6 +27,7 @@ use crate::egl::host_trait::HostTrait;
 use crate::egl::servo_glue::{
     Coordinates, ServoEmbedderCallbacks, ServoGlue, ServoWindowCallbacks,
 };
+use crate::prefs::{parse_command_line_arguments, ArgumentParsingResult};
 
 thread_local! {
     pub static SERVO: RefCell<Option<ServoGlue>> = RefCell::new(None);
@@ -44,7 +41,6 @@ pub struct InitOptions {
     #[cfg(feature = "webxr")]
     pub xr_discovery: Option<webxr::Discovery>,
     pub surfman_integration: SurfmanIntegration,
-    pub prefs: Option<HashMap<String, PrefValue>>,
 }
 
 /// Controls how this embedding's rendering will integrate with the embedder.
@@ -64,17 +60,24 @@ pub fn init(
     crate::init_crypto();
     resources::set(Box::new(ResourceReaderInstance::new()));
 
-    if let Some(prefs) = init_opts.prefs {
-        add_user_prefs(prefs);
-    }
-
+    // `parse_command_line_arguments` expects the first argument to be the binary name.
     let mut args = mem::replace(&mut init_opts.args, vec![]);
-    // opts::from_cmdline_args expects the first argument to be the binary name.
     args.insert(0, "servo".to_string());
-    opts::from_cmdline_args(Options::new(), &args);
+
+    let (opts, preferences, servoshell_preferences) = match parse_command_line_arguments(args) {
+        ArgumentParsingResult::ContentProcess(..) => {
+            unreachable!("Android does not have support for multiprocess yet.")
+        },
+        ArgumentParsingResult::ChromeProcess(opts, preferences, servoshell_preferences) => {
+            (opts, preferences, servoshell_preferences)
+        },
+    };
 
     let embedder_url = init_opts.url.as_ref().and_then(|s| ServoUrl::parse(s).ok());
-    let pref_url = ServoUrl::parse(&pref!(shell.homepage)).ok();
+    let pref_url = servoshell_preferences
+        .url
+        .as_ref()
+        .and_then(|s| ServoUrl::parse(s).ok());
     let blank_url = ServoUrl::parse("about:blank").ok();
 
     let url = embedder_url.or(pref_url).or(blank_url).unwrap();
@@ -117,6 +120,8 @@ pub fn init(
     ));
 
     let servo = Servo::new(
+        opts,
+        preferences,
         rendering_context.clone(),
         embedder_callbacks,
         window_callbacks.clone(),
@@ -125,7 +130,12 @@ pub fn init(
     );
 
     SERVO.with(|s| {
-        let mut servo_glue = ServoGlue::new(rendering_context, servo, window_callbacks, None);
+        let mut servo_glue = ServoGlue::new(
+            rendering_context,
+            servo,
+            window_callbacks,
+            servoshell_preferences,
+        );
         let _ = servo_glue.process_event(EmbedderEvent::NewWebView(url, WebViewId::new()));
         *s.borrow_mut() = Some(servo_glue);
     });
diff --git a/ports/servoshell/egl/ohos/simpleservo.rs b/ports/servoshell/egl/ohos/simpleservo.rs
index d1c153ac2e6..d642db4718f 100644
--- a/ports/servoshell/egl/ohos/simpleservo.rs
+++ b/ports/servoshell/egl/ohos/simpleservo.rs
@@ -17,8 +17,6 @@ use servo::embedder_traits::resources;
 /// and that perform_updates need to be called
 pub use servo::embedder_traits::EventLoopWaker;
 use servo::euclid::Size2D;
-use servo::servo_config::opts;
-use servo::servo_config::opts::ArgumentParsingResult;
 use servo::servo_url::ServoUrl;
 use servo::webrender_traits::RenderingContext;
 use servo::{self, Servo};
@@ -31,6 +29,7 @@ use crate::egl::ohos::InitOpts;
 use crate::egl::servo_glue::{
     Coordinates, ServoEmbedderCallbacks, ServoGlue, ServoWindowCallbacks,
 };
+use crate::prefs::{parse_command_line_arguments, ArgumentParsingResult};
 
 /// Initialize Servo. At that point, we need a valid GL context.
 /// In the future, this will be done in multiple steps.
@@ -46,53 +45,27 @@ pub fn init(
     crate::init_crypto();
     let resource_dir = PathBuf::from(&options.resource_dir).join("servo");
     resources::set(Box::new(ResourceReaderInstance::new(resource_dir)));
-    let mut args = vec!["servoshell".to_string()];
+
     // It would be nice if `from_cmdline_args()` could accept str slices, to avoid allocations here.
     // Then again, this code could and maybe even should be disabled in production builds.
-    let split_args: Vec<String> = options
-        .commandline_args
-        .split("\u{1f}")
-        .map(|arg| arg.to_string())
-        .collect();
-    args.extend(split_args);
-    debug!("Servo commandline args: {:?}", args);
-
-    let mut opts = getopts::Options::new();
-    opts.optopt(
-        "u",
-        "user-agent",
-        "Set custom user agent string (or ios / android / desktop for platform default)",
-        "NCSA Mosaic/1.0 (X11;SunOS 4.1.4 sun4m)",
-    );
-    opts.optmulti(
-        "",
-        "pref",
-        "A preference to set to enable",
-        "dom.bluetooth.enabled",
-    );
-    opts.optmulti(
-        "",
-        "pref",
-        "A preference to set to disable",
-        "dom.webgpu.enabled=false",
-    );
-    opts.optmulti(
-        "",
-        "prefs-file",
-        "Load in additional prefs from a file.",
-        "--prefs-file /path/to/prefs.json",
+    let mut args = vec!["servoshell".to_string()];
+    args.extend(
+        options
+            .commandline_args
+            .split("\u{1f}")
+            .map(|arg| arg.to_string()),
     );
+    debug!("Servo commandline args: {:?}", args);
 
-    let opts_matches = match opts::from_cmdline_args(opts, &args) {
-        ArgumentParsingResult::ContentProcess(matches, _token) => {
-            error!("Content Process mode not supported / tested yet on OpenHarmony!");
-            matches
+    let (opts, preferences, servoshell_preferences) = match parse_command_line_arguments(args) {
+        ArgumentParsingResult::ContentProcess(..) => {
+            unreachable!("OHOS does not have support for multiprocess yet.")
+        },
+        ArgumentParsingResult::ChromeProcess(opts, preferences, servoshell_preferences) => {
+            (opts, preferences, servoshell_preferences)
         },
-        ArgumentParsingResult::ChromeProcess(matches) => matches,
     };
 
-    crate::prefs::register_user_prefs(&opts_matches);
-
     // Initialize surfman
     let connection = Connection::new().or(Err("Failed to create connection"))?;
     let adapter = connection
@@ -144,11 +117,12 @@ pub fn init(
     ));
 
     let servo = Servo::new(
+        opts,
+        preferences,
         rendering_context.clone(),
         embedder_callbacks,
         window_callbacks.clone(),
-        // User agent: Mozilla/5.0 (<Phone|PC|Tablet>; HarmonyOS 5.0) bla bla
-        None,
+        None, /* user_agent */
         CompositeTarget::Window,
     );
 
@@ -156,7 +130,7 @@ pub fn init(
         rendering_context,
         servo,
         window_callbacks,
-        Some(options.resource_dir),
+        servoshell_preferences,
     );
 
     let initial_url = ServoUrl::parse(options.url.as_str())
diff --git a/ports/servoshell/egl/servo_glue.rs b/ports/servoshell/egl/servo_glue.rs
index 042bff8c957..ed3f4ae02a3 100644
--- a/ports/servoshell/egl/servo_glue.rs
+++ b/ports/servoshell/egl/servo_glue.rs
@@ -31,6 +31,7 @@ use servo::webrender_traits::RenderingContext;
 use servo::{Servo, TopLevelBrowsingContextId};
 
 use crate::egl::host_trait::HostTrait;
+use crate::prefs::ServoShellPreferences;
 
 #[derive(Clone, Debug)]
 pub struct Coordinates {
@@ -84,7 +85,6 @@ pub struct ServoGlue {
     need_present: bool,
     callbacks: Rc<ServoWindowCallbacks>,
     events: Vec<EmbedderEvent>,
-    resource_dir: Option<String>,
     context_menu_sender: Option<IpcSender<ContextMenuResult>>,
 
     /// List of top-level browsing contexts.
@@ -98,6 +98,9 @@ pub struct ServoGlue {
     /// The webview that is currently focused.
     /// Modified by EmbedderMsg::WebViewFocused and EmbedderMsg::WebViewBlurred.
     focused_webview_id: Option<WebViewId>,
+
+    /// servoshell specific preferences created during startup of the application.
+    servoshell_preferences: ServoShellPreferences,
 }
 
 #[allow(unused)]
@@ -106,7 +109,7 @@ impl ServoGlue {
         rendering_context: RenderingContext,
         servo: Servo<ServoWindowCallbacks>,
         callbacks: Rc<ServoWindowCallbacks>,
-        resource_dir: Option<String>,
+        servoshell_preferences: ServoShellPreferences,
     ) -> Self {
         Self {
             rendering_context,
@@ -115,11 +118,11 @@ impl ServoGlue {
             need_present: false,
             callbacks,
             events: vec![],
-            resource_dir,
             context_menu_sender: None,
             webviews: HashMap::default(),
             creation_order: vec![],
             focused_webview_id: None,
+            servoshell_preferences,
         }
     }
 
@@ -173,7 +176,7 @@ impl ServoGlue {
     /// Load an URL.
     pub fn load_uri(&mut self, url: &str) -> Result<(), &'static str> {
         info!("load_uri: {}", url);
-        crate::parser::location_bar_input_to_url(url)
+        crate::parser::location_bar_input_to_url(url, &self.servoshell_preferences.searchpage)
             .ok_or("Can't parse URL")
             .and_then(|url| {
                 let browser_id = self.get_browser_id()?;
diff --git a/ports/servoshell/panic_hook.rs b/ports/servoshell/panic_hook.rs
index bb904493beb..7cbf24302af 100644
--- a/ports/servoshell/panic_hook.rs
+++ b/ports/servoshell/panic_hook.rs
@@ -41,6 +41,8 @@ pub(crate) fn panic_hook(info: &PanicHookInfo) {
     }
     drop(stderr);
 
+    // TODO: This shouldn't be using internal Servo options here. Perhaps this functionality should
+    // move into libservo itself.
     if opts::get().hard_fail && !opts::get().multiprocess {
         // When we are exiting due to a hard-failure mode, we trigger a segfault so that crash
         // tests detect that we crashed. If we exit normally it just looks like a non-crash exit.
diff --git a/ports/servoshell/parser.rs b/ports/servoshell/parser.rs
index e1635b0f8fc..d52fc64bead 100644
--- a/ports/servoshell/parser.rs
+++ b/ports/servoshell/parser.rs
@@ -6,7 +6,6 @@
 use std::path::{Path, PathBuf};
 
 use servo::net_traits::pub_domains::is_reg_domain;
-use servo::servo_config::pref;
 use servo::servo_url::ServoUrl;
 
 #[cfg(not(any(target_os = "android", target_env = "ohos")))]
@@ -25,6 +24,7 @@ pub fn get_default_url(
     url_opt: Option<&str>,
     cwd: impl AsRef<Path>,
     exists: impl FnOnce(&PathBuf) -> bool,
+    preferences: &crate::prefs::ServoShellPreferences,
 ) -> ServoUrl {
     // If the url is not provided, we fallback to the homepage in prefs,
     // or a blank page in case the homepage is not set either.
@@ -48,13 +48,10 @@ pub fn get_default_url(
     }
 
     if new_url.is_none() && url_opt.is_some() {
-        new_url = location_bar_input_to_url(url_opt.unwrap());
+        new_url = location_bar_input_to_url(url_opt.unwrap(), &preferences.searchpage);
     }
 
-    let pref_url = {
-        let homepage_url = pref!(shell.homepage);
-        parse_url_or_filename(cwd.as_ref(), &homepage_url).ok()
-    };
+    let pref_url = parse_url_or_filename(cwd.as_ref(), &preferences.homepage).ok();
     let blank_url = ServoUrl::parse("about:blank").ok();
 
     new_url.or(pref_url).or(blank_url).unwrap()
@@ -64,21 +61,15 @@ pub fn get_default_url(
 ///
 /// If this is not a valid URL, try to "fix" it by adding a scheme or if all else fails,
 /// interpret the string as a search term.
-pub fn location_bar_input_to_url(request: &str) -> Option<ServoUrl> {
+pub(crate) fn location_bar_input_to_url(request: &str, searchpage: &str) -> Option<ServoUrl> {
     let request = request.trim();
-    ServoUrl::parse(request)
-        .ok()
-        .or_else(|| {
-            if request.starts_with('/') {
-                ServoUrl::parse(&format!("file://{}", request)).ok()
-            } else if request.contains('/') || is_reg_domain(request) {
-                ServoUrl::parse(&format!("https://{}", request)).ok()
-            } else {
-                None
-            }
-        })
-        .or_else(|| {
-            let url = pref!(shell.searchpage).replace("%s", request);
-            ServoUrl::parse(&url).ok()
-        })
+    ServoUrl::parse(request).ok().or_else(|| {
+        if request.starts_with('/') {
+            ServoUrl::parse(&format!("file://{}", request)).ok()
+        } else if request.contains('/') || is_reg_domain(request) {
+            ServoUrl::parse(&format!("https://{}", request)).ok()
+        } else {
+            ServoUrl::parse(&searchpage.replace("%s", request)).ok()
+        }
+    })
 }
diff --git a/ports/servoshell/prefs.rs b/ports/servoshell/prefs.rs
index 100fa80c4fd..79e7d8540ae 100644
--- a/ports/servoshell/prefs.rs
+++ b/ports/servoshell/prefs.rs
@@ -3,123 +3,737 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use std::collections::HashMap;
-use std::fs::File;
+use std::fs::{read_to_string, File};
 use std::io::Read;
+use std::path::{Path, PathBuf};
+use std::{env, fs, process};
 
-use getopts::Matches;
-use servo::config::opts;
-use servo::config::prefs::{self, PrefValue};
-use servo::servo_config::basedir;
+use euclid::Size2D;
+use getopts::{Matches, Options};
+use log::{error, warn};
+use serde_json::Value;
+use servo::config::opts::{DebugOptions, Opts, OutputOptions};
+use servo::config::prefs::{PrefValue, Preferences};
+use servo::url::ServoUrl;
+use url::Url;
 
-pub fn register_user_prefs(opts_matches: &Matches) {
-    // Read user's prefs.json and then parse --pref command line args.
+pub(crate) struct ServoShellPreferences {
+    /// The user agent to use for servoshell.
+    pub user_agent: Option<String>,
+    /// A URL to load when starting servoshell.
+    pub url: Option<String>,
+    /// An override value for the device pixel ratio.
+    pub device_pixel_ratio_override: Option<f32>,
+    /// Whether or not to attempt clean shutdown.
+    pub clean_shutdown: bool,
+    /// Enable native window's titlebar and decorations.
+    pub no_native_titlebar: bool,
+    /// URL string of the homepage.
+    pub homepage: String,
+    /// URL string of the search engine page with '%s' standing in for the search term.
+    /// For example <https://duckduckgo.com/html/?q=%s>.
+    pub searchpage: String,
+}
+
+impl Default for ServoShellPreferences {
+    fn default() -> Self {
+        Self {
+            user_agent: None,
+            url: None,
+            device_pixel_ratio_override: None,
+            clean_shutdown: false,
+            homepage: "https://servo.org".into(),
+            no_native_titlebar: true,
+            searchpage: "https://duckduckgo.com/html/?q=%s".into(),
+        }
+    }
+}
+
+#[cfg(all(
+    unix,
+    not(target_os = "macos"),
+    not(target_os = "ios"),
+    not(target_os = "android"),
+    not(target_env = "ohos")
+))]
+pub fn default_config_dir() -> Option<PathBuf> {
+    let mut config_dir = ::dirs::config_dir().unwrap();
+    config_dir.push("servo");
+    config_dir.push("default");
+    Some(config_dir)
+}
+
+#[cfg(any(target_os = "android", target_env = "ohos"))]
+pub fn default_config_dir() -> Option<PathBuf> {
+    None
+}
+
+#[cfg(target_os = "macos")]
+pub fn default_config_dir() -> Option<PathBuf> {
+    // FIXME: use `config_dir()` ($HOME/Library/Preferences)
+    // instead of `data_dir()` ($HOME/Library/Application Support) ?
+    let mut config_dir = ::dirs::data_dir().unwrap();
+    config_dir.push("Servo");
+    Some(config_dir)
+}
 
-    let user_prefs_path = opts::get()
-        .config_dir
+#[cfg(target_os = "windows")]
+pub fn default_config_dir() -> Option<PathBuf> {
+    let mut config_dir = ::dirs::config_dir().unwrap();
+    config_dir.push("Servo");
+    Some(config_dir)
+}
+
+/// Get a Servo [`Preferences`] to use when initializing Servo by first reading the user
+/// preferences file and then overriding these preferences with the ones from the `--prefs-file`
+/// command-line argument, if given.
+fn get_preferences(opts_matches: &Matches, config_dir: &Option<PathBuf>) -> Preferences {
+    // Do not read any preferences files from the disk when testing as we do not want it
+    // to throw off test results.
+    if cfg!(test) {
+        return Preferences::default();
+    }
+
+    let user_prefs_path = config_dir
         .clone()
-        .or_else(basedir::default_config_dir)
+        .or_else(default_config_dir)
         .map(|path| path.join("prefs.json"))
         .filter(|path| path.exists());
+    let user_prefs_hash = user_prefs_path.map(read_prefs_file).unwrap_or_default();
+
+    let apply_preferences =
+        |preferences: &mut Preferences, preferences_hash: HashMap<String, PrefValue>| {
+            for (key, value) in preferences_hash.iter() {
+                preferences.set_value(key, value.clone());
+            }
+        };
 
-    let mut userprefs = if let Some(path) = user_prefs_path {
-        read_prefs_file(path.to_str().expect("Failed to read user prefs"))
+    let mut preferences = Preferences::default();
+    apply_preferences(&mut preferences, user_prefs_hash);
+    for pref_file_path in opts_matches.opt_strs("prefs-file").iter() {
+        apply_preferences(&mut preferences, read_prefs_file(pref_file_path))
+    }
+
+    preferences
+}
+
+fn read_prefs_file<P: AsRef<Path>>(path: P) -> HashMap<String, PrefValue> {
+    read_prefs_map(&read_to_string(path).expect("Error opening user prefs"))
+}
+
+pub fn read_prefs_map(txt: &str) -> HashMap<String, PrefValue> {
+    let prefs: HashMap<String, Value> = serde_json::from_str(txt)
+        .map_err(|_| panic!("Could not parse preferences JSON"))
+        .unwrap();
+    prefs
+        .into_iter()
+        .map(|(key, value)| {
+            let value = (&value)
+                .try_into()
+                .map_err(|error| panic!("{error}"))
+                .unwrap();
+            (key, value)
+        })
+        .collect()
+}
+
+#[allow(clippy::large_enum_variant)]
+pub(crate) enum ArgumentParsingResult {
+    ChromeProcess(Opts, Preferences, ServoShellPreferences),
+    ContentProcess(String),
+}
+
+pub(crate) fn parse_command_line_arguments(args: Vec<String>) -> ArgumentParsingResult {
+    let (app_name, args) = args.split_first().unwrap();
+
+    let mut opts = Options::new();
+    opts.optflag("", "legacy-layout", "Use the legacy layout engine");
+    opts.optopt("o", "output", "Output file", "output.png");
+    opts.optopt("s", "size", "Size of tiles", "512");
+    opts.optflagopt(
+        "p",
+        "profile",
+        "Time profiler flag and either a TSV output filename \
+         OR an interval for output to Stdout (blank for Stdout with interval of 5s)",
+        "10 \
+         OR time.tsv",
+    );
+    opts.optflagopt(
+        "",
+        "profiler-trace-path",
+        "Path to dump a self-contained HTML timeline of profiler traces",
+        "",
+    );
+    opts.optflagopt(
+        "m",
+        "memory-profile",
+        "Memory profiler flag and output interval",
+        "10",
+    );
+    opts.optflag("x", "exit", "Exit after load flag");
+    opts.optopt(
+        "y",
+        "layout-threads",
+        "Number of threads to use for layout",
+        "1",
+    );
+    opts.optflag(
+        "i",
+        "nonincremental-layout",
+        "Enable to turn off incremental layout.",
+    );
+    opts.optflagopt(
+        "",
+        "userscripts",
+        "Uses userscripts in resources/user-agent-js, or a specified full path",
+        "",
+    );
+    opts.optmulti(
+        "",
+        "user-stylesheet",
+        "A user stylesheet to be added to every document",
+        "file.css",
+    );
+    opts.optopt(
+        "",
+        "shaders",
+        "Shaders will be loaded from the specified directory instead of using the builtin ones.",
+        "",
+    );
+    opts.optflag("z", "headless", "Headless mode");
+    opts.optflag(
+        "f",
+        "hard-fail",
+        "Exit on thread failure instead of displaying about:failure",
+    );
+    opts.optflag(
+        "F",
+        "soft-fail",
+        "Display about:failure on thread failure instead of exiting",
+    );
+    opts.optflagopt("", "devtools", "Start remote devtools server on port", "0");
+    opts.optflagopt(
+        "",
+        "webdriver",
+        "Start remote WebDriver server on port",
+        "7000",
+    );
+    opts.optopt(
+        "",
+        "window-size",
+        "Set the initial window size in logical (device independenrt) pixels",
+        "1024x740",
+    );
+    opts.optopt(
+        "",
+        "screen-size",
+        "Override the screen resolution in logical (device independent) pixels",
+        "1024x768",
+    );
+    opts.optflag("M", "multiprocess", "Run in multiprocess mode");
+    opts.optflag("B", "bhm", "Background Hang Monitor enabled");
+    opts.optflag("S", "sandbox", "Run in a sandbox if multiprocess");
+    opts.optopt(
+        "",
+        "random-pipeline-closure-probability",
+        "Probability of randomly closing a pipeline (for testing constellation hardening).",
+        "0.0",
+    );
+    opts.optopt(
+        "",
+        "random-pipeline-closure-seed",
+        "A fixed seed for repeatbility of random pipeline closure.",
+        "",
+    );
+    opts.optmulti(
+        "Z",
+        "debug",
+        "A comma-separated string of debug options. Pass help to show available options.",
+        "",
+    );
+    opts.optflag("h", "help", "Print this message");
+    opts.optopt(
+        "",
+        "resources-path",
+        "Path to find static resources",
+        "/home/servo/resources",
+    );
+    opts.optopt(
+        "",
+        "certificate-path",
+        "Path to find SSL certificates",
+        "/home/servo/resources/certs",
+    );
+    opts.optflag(
+        "",
+        "ignore-certificate-errors",
+        "Whether or not to completely ignore certificate errors",
+    );
+    opts.optopt(
+        "",
+        "content-process",
+        "Run as a content process and connect to the given pipe",
+        "servo-ipc-channel.abcdefg",
+    );
+    opts.optopt(
+        "",
+        "config-dir",
+        "config directory following xdg spec on linux platform",
+        "",
+    );
+    opts.optflag("v", "version", "Display servo version information");
+    opts.optflag("", "unminify-js", "Unminify Javascript");
+    opts.optflag("", "print-pwm", "Print Progressive Web Metrics");
+    opts.optopt(
+        "",
+        "local-script-source",
+        "Directory root with unminified scripts",
+        "",
+    );
+    opts.optflag("", "unminify-css", "Unminify Css");
+
+    opts.optflag(
+        "",
+        "clean-shutdown",
+        "Do not shutdown until all threads have finished (macos only)",
+    );
+    opts.optflag("b", "no-native-titlebar", "Do not use native titlebar");
+    opts.optopt("", "device-pixel-ratio", "Device pixels per px", "");
+    opts.optopt(
+        "u",
+        "user-agent",
+        "Set custom user agent string (or ios / android / desktop for platform default)",
+        "NCSA Mosaic/1.0 (X11;SunOS 4.1.4 sun4m)",
+    );
+    opts.optmulti(
+        "",
+        "pref",
+        "A preference to set to enable",
+        "dom.bluetooth.enabled",
+    );
+    opts.optmulti(
+        "",
+        "pref",
+        "A preference to set to disable",
+        "dom.webgpu.enabled=false",
+    );
+    opts.optmulti(
+        "",
+        "prefs-file",
+        "Load in additional prefs from a file.",
+        "--prefs-file /path/to/prefs.json",
+    );
+
+    let opt_match = match opts.parse(args) {
+        Ok(m) => m,
+        Err(f) => args_fail(&f.to_string()),
+    };
+
+    if opt_match.opt_present("v") || opt_match.opt_present("version") {
+        println!("{}", crate::servo_version());
+        process::exit(0);
+    }
+
+    if opt_match.opt_present("h") || opt_match.opt_present("help") {
+        print_usage(app_name, &opts);
+        process::exit(0);
+    };
+
+    let config_dir = opt_match.opt_str("config-dir").map(Into::into);
+    let mut preferences = get_preferences(&opt_match, &config_dir);
+
+    // If this is the content process, we'll receive the real options over IPC. So just fill in
+    // some dummy options for now.
+    if let Some(content_process) = opt_match.opt_str("content-process") {
+        return ArgumentParsingResult::ContentProcess(content_process);
+    }
+
+    let mut debug_options = DebugOptions::default();
+    for debug_string in opt_match.opt_strs("Z") {
+        if let Err(e) = debug_options.extend(debug_string) {
+            args_fail(&format!("error: unrecognized debug option: {}", e));
+        }
+    }
+
+    if debug_options.help {
+        print_debug_options_usage(app_name);
+    }
+
+    let tile_size: usize = match opt_match.opt_str("s") {
+        Some(tile_size_str) => tile_size_str
+            .parse()
+            .unwrap_or_else(|err| args_fail(&format!("Error parsing option: -s ({})", err))),
+        None => 512,
+    };
+
+    // If only the flag is present, default to a 5 second period for both profilers
+    let time_profiling = if opt_match.opt_present("p") {
+        match opt_match.opt_str("p") {
+            Some(argument) => match argument.parse::<f64>() {
+                Ok(interval) => Some(OutputOptions::Stdout(interval)),
+                Err(_) => match ServoUrl::parse(&argument) {
+                    Ok(_) => panic!("influxDB isn't supported anymore"),
+                    Err(_) => Some(OutputOptions::FileName(argument)),
+                },
+            },
+            None => Some(OutputOptions::Stdout(5.0)),
+        }
     } else {
-        HashMap::new()
+        // if the p option doesn't exist:
+        None
     };
 
-    let prefs_from_files: Vec<HashMap<String, PrefValue>> = opts_matches
-        .opt_strs("prefs-file")
-        .iter()
-        .map(|path| read_prefs_file(path))
-        .collect();
+    if let Some(ref time_profiler_trace_path) = opt_match.opt_str("profiler-trace-path") {
+        let mut path = PathBuf::from(time_profiler_trace_path);
+        path.pop();
+        if let Err(why) = fs::create_dir_all(&path) {
+            error!(
+                "Couldn't create/open {:?}: {:?}",
+                Path::new(time_profiler_trace_path).to_string_lossy(),
+                why
+            );
+        }
+    }
+
+    let mem_profiler_period = opt_match.opt_default("m", "5").map(|period| {
+        period
+            .parse()
+            .unwrap_or_else(|err| args_fail(&format!("Error parsing option: -m ({})", err)))
+    });
 
-    let argprefs: HashMap<String, PrefValue> = opts_matches
-        .opt_strs("pref")
+    let mut layout_threads: Option<usize> = opt_match.opt_str("y").map(|layout_threads_str| {
+        layout_threads_str
+            .parse()
+            .unwrap_or_else(|err| args_fail(&format!("Error parsing option: -y ({})", err)))
+    });
+
+    let nonincremental_layout = opt_match.opt_present("i");
+
+    let random_pipeline_closure_probability = opt_match
+        .opt_str("random-pipeline-closure-probability")
+        .map(|prob| {
+            prob.parse().unwrap_or_else(|err| {
+                args_fail(&format!(
+                    "Error parsing option: --random-pipeline-closure-probability ({})",
+                    err
+                ))
+            })
+        });
+
+    let random_pipeline_closure_seed =
+        opt_match
+            .opt_str("random-pipeline-closure-seed")
+            .map(|seed| {
+                seed.parse().unwrap_or_else(|err| {
+                    args_fail(&format!(
+                        "Error parsing option: --random-pipeline-closure-seed ({})",
+                        err
+                    ))
+                })
+            });
+
+    if debug_options.trace_layout {
+        layout_threads = Some(1);
+    }
+
+    if opt_match.opt_present("devtools") {
+        let port = opt_match
+            .opt_str("devtools")
+            .map(|port| {
+                port.parse().unwrap_or_else(|err| {
+                    args_fail(&format!("Error parsing option: --devtools ({})", err))
+                })
+            })
+            .unwrap_or(preferences.devtools_server_port);
+        preferences.devtools_server_enabled = true;
+        preferences.devtools_server_port = port;
+    }
+
+    let webdriver_port = opt_match.opt_default("webdriver", "7000").map(|port| {
+        port.parse().unwrap_or_else(|err| {
+            args_fail(&format!("Error parsing option: --webdriver ({})", err))
+        })
+    });
+
+    let parse_resolution_string = |string: String| {
+        let components: Vec<u32> = string
+            .split('x')
+            .map(|component| {
+                component.parse().unwrap_or_else(|error| {
+                    args_fail(&format!("Error parsing resolution '{string}': {error}"));
+                })
+            })
+            .collect();
+        Size2D::new(components[0], components[1])
+    };
+
+    let screen_size_override = opt_match
+        .opt_str("screen-size")
+        .map(parse_resolution_string);
+
+    // Make sure the default window size is not larger than any provided screen size.
+    let default_window_size = Size2D::new(1024, 740);
+    let default_window_size = screen_size_override
+        .map_or(default_window_size, |screen_size_override| {
+            default_window_size.min(screen_size_override)
+        });
+
+    let initial_window_size = opt_match
+        .opt_str("window-size")
+        .map_or(default_window_size, parse_resolution_string);
+
+    let user_stylesheets = opt_match
+        .opt_strs("user-stylesheet")
         .iter()
-        .map(|pref| {
-            let split: Vec<&str> = pref.splitn(2, '=').collect();
-            let pref_name = split[0];
-            let pref_value = match split.get(1).cloned() {
-                Some("true") | None => PrefValue::Bool(true),
-                Some("false") => PrefValue::Bool(false),
-                Some(string) => {
-                    if let Ok(int) = string.parse::<i64>() {
-                        PrefValue::Int(int)
-                    } else if let Ok(float) = string.parse::<f64>() {
-                        PrefValue::Float(float)
-                    } else {
-                        PrefValue::from(string)
-                    }
-                },
-            };
-            (pref_name.to_string(), pref_value)
+        .map(|filename| {
+            let cwd = env::current_dir().unwrap();
+            let path = cwd.join(filename);
+            let url = ServoUrl::from_url(Url::from_file_path(&path).unwrap());
+            let mut contents = Vec::new();
+            File::open(path)
+                .unwrap_or_else(|err| args_fail(&format!("Couldn't open {}: {}", filename, err)))
+                .read_to_end(&mut contents)
+                .unwrap_or_else(|err| args_fail(&format!("Couldn't read {}: {}", filename, err)));
+            (contents, url)
         })
         .collect();
 
-    // Apply --prefs-file prefs first
-    for prefs in prefs_from_files {
-        userprefs.extend(prefs);
+    // Handle all command-line preferences overrides.
+    for pref in opt_match.opt_strs("pref") {
+        let split: Vec<&str> = pref.splitn(2, '=').collect();
+        let pref_name = split[0];
+        let pref_value = PrefValue::from_booleanish_str(split.get(1).copied().unwrap_or("true"));
+        preferences.set_value(pref_name, pref_value);
     }
 
-    // Then apply individually passed prefs from --pref
-    userprefs.extend(argprefs);
+    let legacy_layout = opt_match.opt_present("legacy-layout");
+    if legacy_layout {
+        preferences.layout_legacy_layout = true;
+    }
 
-    prefs::add_user_prefs(userprefs);
+    if let Some(layout_threads) = layout_threads {
+        preferences.layout_threads = layout_threads as i64;
+    }
+
+    let no_native_titlebar = opt_match.opt_present("no-native-titlebar");
+    let mut device_pixel_ratio_override = opt_match.opt_str("device-pixel-ratio").map(|dppx_str| {
+        dppx_str.parse().unwrap_or_else(|err| {
+            error!("Error parsing option: --device-pixel-ratio ({})", err);
+            process::exit(1);
+        })
+    });
+
+    // If an output file is specified the device pixel ratio is always 1.
+    let output_file = opt_match.opt_str("o");
+    if output_file.is_some() {
+        device_pixel_ratio_override = Some(1.0);
+    }
+
+    let url = if !opt_match.free.is_empty() {
+        Some(opt_match.free[0][..].into())
+    } else {
+        None
+    };
+
+    // FIXME: enable JIT compilation on 32-bit Android after the startup crash issue (#31134) is fixed.
+    if cfg!(target_os = "android") && cfg!(target_pointer_width = "32") {
+        preferences.js_baseline_interpreter_enabled = false;
+        preferences.js_baseline_jit_enabled = false;
+        preferences.js_ion_enabled = false;
+    }
+
+    let servoshell_preferences = ServoShellPreferences {
+        user_agent: opt_match.opt_str("u"),
+        url,
+        no_native_titlebar,
+        device_pixel_ratio_override,
+        clean_shutdown: opt_match.opt_present("clean-shutdown"),
+        ..Default::default()
+    };
+
+    let headless = opt_match.opt_present("z");
+    if headless && preferences.media_glvideo_enabled {
+        warn!("GL video rendering is not supported on headless windows.");
+        preferences.media_glvideo_enabled = false;
+    }
+
+    let opts = Opts {
+        debug: debug_options.clone(),
+        legacy_layout,
+        tile_size,
+        time_profiling,
+        time_profiler_trace_path: opt_match.opt_str("profiler-trace-path"),
+        mem_profiler_period,
+        nonincremental_layout,
+        userscripts: opt_match.opt_default("userscripts", ""),
+        user_stylesheets,
+        output_file,
+        headless,
+        hard_fail: opt_match.opt_present("f") && !opt_match.opt_present("F"),
+        webdriver_port,
+        initial_window_size,
+        screen_size_override,
+        multiprocess: opt_match.opt_present("M"),
+        background_hang_monitor: opt_match.opt_present("B"),
+        sandbox: opt_match.opt_present("S"),
+        random_pipeline_closure_probability,
+        random_pipeline_closure_seed,
+        exit_after_load: opt_match.opt_present("x"),
+        config_dir,
+        shaders_dir: opt_match.opt_str("shaders").map(Into::into),
+        certificate_path: opt_match.opt_str("certificate-path"),
+        ignore_certificate_errors: opt_match.opt_present("ignore-certificate-errors"),
+        unminify_js: opt_match.opt_present("unminify-js"),
+        local_script_source: opt_match.opt_str("local-script-source"),
+        unminify_css: opt_match.opt_present("unminify-css"),
+        print_pwm: opt_match.opt_present("print-pwm"),
+    };
+
+    ArgumentParsingResult::ChromeProcess(opts, preferences, servoshell_preferences)
 }
 
-fn read_prefs_file(path: &str) -> HashMap<String, PrefValue> {
-    let mut file = File::open(path).expect("Error opening user prefs");
-    let mut txt = String::new();
-    file.read_to_string(&mut txt)
-        .expect("Can't read user prefs file");
-    prefs::read_prefs_map(&txt).expect("Can't parse user prefs file")
+fn args_fail(msg: &str) -> ! {
+    eprintln!("{}", msg);
+    process::exit(1)
+}
+
+fn print_usage(app: &str, opts: &Options) {
+    let message = format!(
+        "Usage: {} [ options ... ] [URL]\n\twhere options include",
+        app
+    );
+    println!("{}", opts.usage(&message));
+}
+
+fn print_debug_options_usage(app: &str) {
+    fn print_option(name: &str, description: &str) {
+        println!("\t{:<35} {}", name, description);
+    }
+
+    println!(
+        "Usage: {} debug option,[options,...]\n\twhere options include\n\nOptions:",
+        app
+    );
+
+    print_option(
+        "bubble-inline-sizes-separately",
+        "Bubble intrinsic widths separately like other engines.",
+    );
+    print_option(
+        "convert-mouse-to-touch",
+        "Send touch events instead of mouse events",
+    );
+    print_option(
+        "disable-canvas-aa",
+        "Disable antialiasing on the HTML canvas element.",
+    );
+    print_option(
+        "disable-share-style-cache",
+        "Disable the style sharing cache.",
+    );
+    print_option(
+        "disable-subpixel-aa",
+        "Disable subpixel text antialiasing overriding preference.",
+    );
+    print_option("disable-text-aa", "Disable antialiasing of rendered text.");
+    print_option(
+        "dump-stacking-context-tree",
+        "Print the stacking context tree after each layout.",
+    );
+    print_option(
+        "dump-display-list",
+        "Print the display list after each layout.",
+    );
+    print_option(
+        "dump-display-list-json",
+        "Print the display list in JSON form.",
+    );
+    print_option(
+        "dump-flow-tree",
+        "Print the flow tree (Layout 2013) or fragment tree (Layout 2020) after each layout.",
+    );
+    print_option(
+        "dump-rule-tree",
+        "Print the style rule tree after each layout.",
+    );
+    print_option(
+        "dump-style-tree",
+        "Print the DOM with computed styles after each restyle.",
+    );
+    print_option("dump-style-stats", "Print style statistics each restyle.");
+    print_option("gc-profile", "Log GC passes and their durations.");
+    print_option(
+        "load-webfonts-synchronously",
+        "Load web fonts synchronously to avoid non-deterministic network-driven reflows",
+    );
+    print_option(
+        "parallel-display-list-building",
+        "Build display lists in parallel.",
+    );
+    print_option("precache-shaders", "Compile all shaders during init.");
+    print_option(
+        "profile-script-events",
+        "Enable profiling of script-related events.",
+    );
+    print_option(
+        "relayout-event",
+        "Print notifications when there is a relayout.",
+    );
+    print_option("replace-surrogates", "Replace unpaires surrogates in DOM strings with U+FFFD. See https://github.com/servo/servo/issues/6564");
+    print_option(
+        "show-fragment-borders",
+        "Paint borders along fragment boundaries.",
+    );
+    print_option(
+        "show-parallel-layout",
+        "Mark which thread laid each flow out with colors.",
+    );
+    print_option(
+        "signpost",
+        "Emit native OS signposts for profile events (currently macOS only)",
+    );
+    print_option(
+        "trace-layout",
+        "Write layout trace to an external file for debugging.",
+    );
+    print_option("wr-stats", "Show WebRender profiler on screen.");
+
+    println!();
+
+    process::exit(0)
 }
 
 #[cfg(test)]
-fn test_parse_pref(arg: &str) {
-    let mut opts = getopts::Options::new();
-    opts.optmulti("", "pref", "", "");
-    opts.optmulti("", "prefs-file", "", "");
+fn test_parse_pref(arg: &str) -> Preferences {
     let args = vec!["servo".to_string(), "--pref".to_string(), arg.to_string()];
-    let matches = match opts::from_cmdline_args(opts, &args) {
-        opts::ArgumentParsingResult::ContentProcess(m, _) => m,
-        opts::ArgumentParsingResult::ChromeProcess(m) => m,
-    };
-    register_user_prefs(&matches);
+    match parse_command_line_arguments(args) {
+        ArgumentParsingResult::ContentProcess(..) => {
+            unreachable!("No preferences for content process")
+        },
+        ArgumentParsingResult::ChromeProcess(_, preferences, _) => preferences,
+    }
 }
 
 #[test]
 fn test_parse_pref_from_command_line() {
-    use servo::servo_config::pref;
     // Test with boolean values.
-    test_parse_pref("dom.bluetooth.enabled=true");
-    assert_eq!(
-        prefs::pref_map().get("dom.bluetooth.enabled"),
-        PrefValue::Bool(true)
-    );
-    assert!(pref!(dom.bluetooth.enabled));
+    let preferences = test_parse_pref("dom_bluetooth_enabled=true");
+    assert!(preferences.dom_bluetooth_enabled);
 
-    test_parse_pref("dom.bluetooth.enabled=false");
-    assert_eq!(
-        prefs::pref_map().get("dom.bluetooth.enabled"),
-        PrefValue::Bool(false)
-    );
-    assert_eq!(pref!(dom.bluetooth.enabled), false);
+    let preferences = test_parse_pref("dom_bluetooth_enabled=false");
+    assert!(!preferences.dom_bluetooth_enabled);
 
     // Test with numbers
-    test_parse_pref("layout.threads=42");
-    assert_eq!(pref!(layout.threads), 42);
+    let preferences = test_parse_pref("layout_threads=42");
+    assert_eq!(preferences.layout_threads, 42);
 
     // Test string.
-    test_parse_pref("shell.homepage=str");
-    assert_eq!(pref!(shell.homepage), "str");
+    let preferences = test_parse_pref("fonts_default=Lucida");
+    assert_eq!(preferences.fonts_default, "Lucida");
 
     // Test with no value (defaults to true).
-    prefs::pref_map()
-        .set("dom.bluetooth.enabled", false)
-        .unwrap();
-    test_parse_pref("dom.bluetooth.enabled");
-    assert!(pref!(dom.bluetooth.enabled));
+    let preferences = test_parse_pref("dom_bluetooth_enabled");
+    assert!(preferences.dom_bluetooth_enabled);
 }
 
 #[test]
@@ -130,12 +744,18 @@ fn test_invalid_prefs_from_command_line_panics() {
     .err()
     .and_then(|a| a.downcast_ref::<String>().cloned())
     .expect("Should panic");
-    assert!(
-        err_msg.starts_with("Error setting preference"),
+    assert_eq!(
+        err_msg, "Unknown preference: \"doesntexist\"",
         "Message should describe the problem"
-    );
-    assert!(
-        err_msg.contains("doesntexist"),
-        "Message should mention the name of the preference"
-    );
+    )
+}
+
+#[test]
+fn test_create_prefs_map() {
+    let json_str = "{
+        \"layout.writing-mode.enabled\": true,
+        \"network.mime.sniff\": false,
+        \"shell.homepage\": \"https://servo.org\"
+    }";
+    assert_eq!(read_prefs_map(json_str).len(), 3);
 }
diff --git a/ports/servoshell/test.rs b/ports/servoshell/test.rs
index 0ee94d44829..0ff470f8b90 100644
--- a/ports/servoshell/test.rs
+++ b/ports/servoshell/test.rs
@@ -89,15 +89,17 @@ fn test_argument_parsing_special() {
 // Helper function to test url
 fn test_url(input: &str, location: &str, cmdline_if_exists: &str, cmdline_otherwise: &str) {
     assert_eq!(
-        location_bar_input_to_url(input).unwrap().into_string(),
+        location_bar_input_to_url(input, "https://duckduckgo.com/html/?q=%s")
+            .unwrap()
+            .into_string(),
         location
     );
     assert_eq!(
-        get_default_url(Some(input), FAKE_CWD, |_| true).into_string(),
+        get_default_url(Some(input), FAKE_CWD, |_| true, &Default::default()).into_string(),
         cmdline_if_exists
     );
     assert_eq!(
-        get_default_url(Some(input), FAKE_CWD, |_| false).into_string(),
+        get_default_url(Some(input), FAKE_CWD, |_| false, &Default::default()).into_string(),
         cmdline_otherwise
     );
 }
diff --git a/resources/prefs.json b/resources/prefs.json
index d831ccf4d6a..3ae80ab9da7 100644
--- a/resources/prefs.json
+++ b/resources/prefs.json
@@ -1,135 +1,135 @@
 {
-  "devtools.server.enabled": false,
-  "devtools.server.port": 0,
-  "dom.abort_controller.enabled": false,
-  "dom.allow_scripts_to_close_windows": false,
-  "dom.bluetooth.enabled": false,
-  "dom.bluetooth.testing.enabled": false,
-  "dom.canvas_capture.enabled": false,
-  "dom.canvas_text.enabled": true,
-  "dom.compositionevent.enabled": false,
-  "dom.crypto.subtle.enabled": true,
-  "dom.customelements.enabled": true,
-  "dom.document.dblclick_dist": 1,
-  "dom.document.dblclick_timeout": 300,
-  "dom.forcetouch.enabled": false,
-  "dom.fullscreen.test": false,
-  "dom.gamepad.enabled": true,
-  "dom.imagebitmap.enabled": false,
-  "dom.intersection_observer.enabled": false,
-  "dom.microdata.enabled": false,
-  "dom.microdata.testing.enabled": false,
-  "dom.mouseevent.which.enabled": false,
-  "dom.mutation_observer.enabled": true,
-  "dom.offscreen_canvas.enabled": false,
-  "dom.permissions.enabled": false,
-  "dom.permissions.testing.allowed_in_nonsecure_contexts": false,
-  "dom.resize_observer.enabled": false,
-  "dom.script.asynch": true,
-  "dom.serviceworker.enabled": false,
-  "dom.serviceworker.timeout_seconds": 60,
-  "dom.servo_helpers.enabled": false,
-  "dom.servoparser.async_html_tokenizer.enabled": false,
-  "dom.shadowdom.enabled": false,
-  "dom.svg.enabled": false,
-  "dom.testable_crash.enabled": false,
-  "dom.testbinding.enabled": false,
-  "dom.testing.htmlinputelement.select_files.enabled": false,
-  "dom.webgl2.enabled": false,
-  "dom.webgpu.enabled": false,
-  "dom.webgpu.wgpu_backend": "",
-  "dom.webrtc.enabled": false,
-  "dom.webrtc.transceiver.enabled": false,
-  "dom.webvtt.enabled": false,
-  "dom.webxr.enabled": true,
-  "dom.webxr.first_person_observer_view": false,
-  "dom.webxr.glwindow.cubemap": false,
-  "dom.webxr.glwindow.enabled": true,
-  "dom.webxr.glwindow.left-right": false,
-  "dom.webxr.glwindow.red-cyan": false,
-  "dom.webxr.glwindow.spherical": false,
-  "dom.webxr.hands.enabled": true,
-  "dom.webxr.layers.enabled": false,
-  "dom.webxr.openxr.enabled": true,
-  "dom.webxr.sessionavailable": false,
-  "dom.webxr.test": false,
-  "dom.webxr.unsafe-assume-user-intent": false,
-  "dom.worklet.timeout_ms": 10,
-  "dom.xpath.enabled": false,
-  "gfx.subpixel-text-antialiasing.enabled": true,
-  "gfx.texture-swizzling.enabled": true,
-  "js.asmjs.enabled": true,
-  "js.asyncstack.enabled": false,
-  "js.baseline_interpreter.enabled": true,
-  "js.baseline_jit.enabled": true,
-  "js.baseline_jit.unsafe_eager_compilation.enabled": false,
-  "js.disable_jit": false,
-  "js.discard_system_source.enabled": false,
-  "js.dump_stack_on_debuggee_would_run.enabled": false,
-  "js.ion.enabled": true,
-  "js.ion.offthread_compilation.enabled": true,
-  "js.ion.unsafe_eager_compilation.enabled": false,
-  "js.mem.gc.allocation_threshold_avoid_interrupt_factor": 100,
-  "js.mem.gc.allocation_threshold_factor": 100,
-  "js.mem.gc.allocation_threshold_mb": 30,
-  "js.mem.gc.compacting.enabled": true,
-  "js.mem.gc.decommit_threshold_mb": 32,
-  "js.mem.gc.dynamic_heap_growth.enabled": true,
-  "js.mem.gc.dynamic_mark_slice.enabled": true,
-  "js.mem.gc.empty_chunk_count_max": 30,
-  "js.mem.gc.empty_chunk_count_min": 1,
-  "js.mem.gc.high_frequency_heap_growth_max": 300,
-  "js.mem.gc.high_frequency_heap_growth_min": 150,
-  "js.mem.gc.high_frequency_high_limit_mb": 500,
-  "js.mem.gc.high_frequency_low_limit_mb": 100,
-  "js.mem.gc.high_frequency_time_limit_ms": 1000,
-  "js.mem.gc.incremental.enabled": true,
-  "js.mem.gc.incremental.slice_ms": 10,
-  "js.mem.gc.low_frequency_heap_growth": 150,
-  "js.mem.gc.per_zone.enabled": false,
-  "js.mem.gc.zeal.frequency": 100,
-  "js.mem.gc.zeal.level": 0,
-  "js.mem.max": -1,
-  "js.native_regex.enabled": true,
-  "js.offthread_compilation.enabled": true,
-  "js.parallel_parsing.enabled": true,
-  "js.shared_memory.enabled": true,
-  "js.throw_on_asmjs_validation_failure.enabled": false,
-  "js.throw_on_debuggee_would_run.enabled": false,
-  "js.timers.minimum_duration": 1000,
-  "js.wasm.baseline.enabled": true,
-  "js.wasm.enabled": true,
-  "js.wasm.ion.enabled": true,
-  "js.werror.enabled": false,
-  "layout.animations.test.enabled": false,
-  "layout.columns.enabled": false,
-  "layout.css.transition-behavior.enabled": true,
-  "layout.flexbox.enabled": true,
-  "layout.grid.enabled": false,
-  "layout.legacy_layout": false,
-  "layout.threads": 3,
-  "layout.writing-mode.enabled": false,
-  "media.glvideo.enabled": false,
-  "media.testing.enabled": false,
-  "network.enforce_tls.enabled": false,
-  "network.enforce_tls.localhost": false,
-  "network.enforce_tls.onion": false,
-  "network.http-cache.disabled": false,
-  "network.local_directory_listing.enabled": false,
-  "network.mime.sniff": false,
-  "network.tls.ignore_unexpected_eof": false,
-  "session-history.max-length": 20,
-  "shell.background-color.rgba": [1.0, 1.0, 1.0, 1.0],
-  "shell.crash_reporter.enabled": false,
-  "shell.homepage": "https://servo.org",
-  "shell.keep_screen_on.enabled": false,
-  "shell.native-orientation": "both",
-  "shell.native-titlebar.enabled": true,
-  "shell.searchpage": "https://duckduckgo.com/html/?q=%s",
-  "threadpools.async_runtime_workers.max": 6,
-  "threadpools.fallback_worker_num": 3,
-  "threadpools.image_cache_workers.max": 4,
-  "threadpools.resource_workers.max": 4,
-  "threadpools.webrender_workers.max": 4,
-  "webgl.testing.context_creation_error": false
+  "devtools_server_enabled": false,
+  "devtools_server_port": 0,
+  "dom_abort_controller_enabled": false,
+  "dom_allow_scripts_to_close_windows": false,
+  "dom_bluetooth_enabled": false,
+  "dom_bluetooth_testing_enabled": false,
+  "dom_canvas_capture_enabled": false,
+  "dom_canvas_text_enabled": true,
+  "dom_compositionevent_enabled": false,
+  "dom_crypto_subtle_enabled": true,
+  "dom_customelements_enabled": true,
+  "dom_document_dblclick_dist": 1,
+  "dom_document_dblclick_timeout": 300,
+  "dom_forcetouch_enabled": false,
+  "dom_fullscreen_test": false,
+  "dom_gamepad_enabled": true,
+  "dom_imagebitmap_enabled": false,
+  "dom_intersection_observer_enabled": false,
+  "dom_microdata_enabled": false,
+  "dom_microdata_testing_enabled": false,
+  "dom_mouse_event_which_enabled": false,
+  "dom_mutation_observer_enabled": true,
+  "dom_offscreen_canvas_enabled": false,
+  "dom_permissions_enabled": false,
+  "dom_permissions_testing_allowed_in_nonsecure_contexts": false,
+  "dom_resize_observer_enabled": false,
+  "dom_script_asynch": true,
+  "dom_serviceworker_enabled": false,
+  "dom_serviceworker_timeout_seconds": 60,
+  "dom_servo_helpers_enabled": false,
+  "dom_servoparser_async_html_tokenizer_enabled": false,
+  "dom_shadowdom_enabled": false,
+  "dom_svg_enabled": false,
+  "dom_testable_crash_enabled": false,
+  "dom_testbinding_enabled": false,
+  "dom_testing_html_input_element_select_files_enabled": false,
+  "dom_webgl2_enabled": false,
+  "dom_webgpu_enabled": false,
+  "dom_webgpu_wgpu_backend": "",
+  "dom_webrtc_enabled": false,
+  "dom_webrtc_transceiver_enabled": false,
+  "dom_webvtt_enabled": false,
+  "dom_webxr_enabled": true,
+  "dom_webxr_first_person_observer_view": false,
+  "dom_webxr_glwindow_cubemap": false,
+  "dom_webxr_glwindow_enabled": true,
+  "dom_webxr_glwindow_left-right": false,
+  "dom_webxr_glwindow_red-cyan": false,
+  "dom_webxr_glwindow_spherical": false,
+  "dom_webxr_hands_enabled": true,
+  "dom_webxr_layers_enabled": false,
+  "dom_webxr_openxr_enabled": true,
+  "dom_webxr_sessionavailable": false,
+  "dom_webxr_test": false,
+  "dom_webxr_unsafe-assume-user-intent": false,
+  "dom_worklet_timeout_ms": 10,
+  "dom_xpath_enabled": false,
+  "gfx_subpixel-text-antialiasing_enabled": true,
+  "gfx_texture-swizzling_enabled": true,
+  "js_asmjs_enabled": true,
+  "js_asyncstack_enabled": false,
+  "js_baseline_interpreter_enabled": true,
+  "js_baseline_jit_enabled": true,
+  "js_baseline_jit_unsafe_eager_compilation_enabled": false,
+  "js_disable_jit": false,
+  "js_discard_system_source_enabled": false,
+  "js_dump_stack_on_debuggee_would_run_enabled": false,
+  "js_ion_enabled": true,
+  "js_ion_offthread_compilation_enabled": true,
+  "js_ion_unsafe_eager_compilation_enabled": false,
+  "js_mem_gc_allocation_threshold_avoid_interrupt_factor": 100,
+  "js_mem_gc_allocation_threshold_factor": 100,
+  "js_mem_gc_allocation_threshold_mb": 30,
+  "js_mem_gc_compacting_enabled": true,
+  "js_mem_gc_decommit_threshold_mb": 32,
+  "js_mem_gc_dynamic_heap_growth_enabled": true,
+  "js_mem_gc_dynamic_mark_slice_enabled": true,
+  "js_mem_gc_empty_chunk_count_max": 30,
+  "js_mem_gc_empty_chunk_count_min": 1,
+  "js_mem_gc_high_frequency_heap_growth_max": 300,
+  "js_mem_gc_high_frequency_heap_growth_min": 150,
+  "js_mem_gc_high_frequency_high_limit_mb": 500,
+  "js_mem_gc_high_frequency_low_limit_mb": 100,
+  "js_mem_gc_high_frequency_time_limit_ms": 1000,
+  "js_mem_gc_incremental_enabled": true,
+  "js_mem_gc_incremental_slice_ms": 10,
+  "js_mem_gc_low_frequency_heap_growth": 150,
+  "js_mem_gc_per_zone_enabled": false,
+  "js_mem_gc_zeal_frequency": 100,
+  "js_mem_gc_zeal_level": 0,
+  "js_mem_max": -1,
+  "js_native_regex_enabled": true,
+  "js_offthread_compilation_enabled": true,
+  "js_parallel_parsing_enabled": true,
+  "js_shared_memory_enabled": true,
+  "js_throw_on_asmjs_validation_failure_enabled": false,
+  "js_throw_on_debuggee_would_run_enabled": false,
+  "js_timers_minimum_duration": 1000,
+  "js_wasm_baseline_enabled": true,
+  "js_wasm_enabled": true,
+  "js_wasm_ion_enabled": true,
+  "js_werror_enabled": false,
+  "layout_animations_test_enabled": false,
+  "layout_columns_enabled": false,
+  "layout_css_transition-behavior_enabled": true,
+  "layout_flexbox_enabled": true,
+  "layout_grid_enabled": false,
+  "layout_legacy_layout": false,
+  "layout_threads": 3,
+  "layout_writing-mode_enabled": false,
+  "media_glvideo_enabled": false,
+  "media_testing_enabled": false,
+  "network_enforce_tls_enabled": false,
+  "network_enforce_tls_localhost": false,
+  "network_enforce_tls_onion": false,
+  "network_http-cache_disabled": false,
+  "network_local_directory_listing_enabled": false,
+  "network_mime_sniff": false,
+  "network_tls_ignore_unexpected_eof": false,
+  "session-history_max-length": 20,
+  "shell_background-color_rgba": [1.0, 1.0, 1.0, 1.0],
+  "shell_crash_reporter_enabled": false,
+  "shell_homepage": "https://servo_org",
+  "shell_keep_screen_on_enabled": false,
+  "shell_native-orientation": "both",
+  "shell_native-titlebar_enabled": true,
+  "shell_searchpage": "https://duckduckgo_com/html/?q=%s",
+  "threadpools_async_runtime_workers_max": 6,
+  "threadpools_fallback_worker_num": 3,
+  "threadpools_image_cache_workers_max": 4,
+  "threadpools_resource_workers_max": 4,
+  "threadpools_webrender_workers_max": 4,
+  "webgl_testing_context_creation_error": false
 }
diff --git a/resources/wpt-prefs.json b/resources/wpt-prefs.json
index bb3185e2630..6de7b9efbf1 100644
--- a/resources/wpt-prefs.json
+++ b/resources/wpt-prefs.json
@@ -1,4 +1,4 @@
 {
-  "dom.webxr.test": true,
-  "network.tls.ignore_unexpected_eof": true
+  "dom_webxr_test": true,
+  "network_tls_ignore_unexpected_eof": true
 }
diff --git a/tests/wpt/meta-legacy-layout/WebCryptoAPI/__dir__.ini b/tests/wpt/meta-legacy-layout/WebCryptoAPI/__dir__.ini
index 71feefa5fb7..67f689a6cde 100644
--- a/tests/wpt/meta-legacy-layout/WebCryptoAPI/__dir__.ini
+++ b/tests/wpt/meta-legacy-layout/WebCryptoAPI/__dir__.ini
@@ -1 +1 @@
-prefs: [dom.crypto.subtle.enabled: true]
\ No newline at end of file
+prefs: [dom_crypto_subtle_enabled: true]
\ No newline at end of file
diff --git a/tests/wpt/meta-legacy-layout/__dir__.ini b/tests/wpt/meta-legacy-layout/__dir__.ini
index 60a490fc6ff..c512e4494a3 100644
--- a/tests/wpt/meta-legacy-layout/__dir__.ini
+++ b/tests/wpt/meta-legacy-layout/__dir__.ini
@@ -1 +1 @@
-prefs: ["dom.imagebitmap.enabled:true"]
+prefs: ["dom_imagebitmap_enabled:true"]
diff --git a/tests/wpt/meta-legacy-layout/bluetooth/__dir__.ini b/tests/wpt/meta-legacy-layout/bluetooth/__dir__.ini
index dfe57e6fd66..bc634adeb33 100644
--- a/tests/wpt/meta-legacy-layout/bluetooth/__dir__.ini
+++ b/tests/wpt/meta-legacy-layout/bluetooth/__dir__.ini
@@ -1 +1 @@
-prefs: ["dom.bluetooth.enabled:true"]
+prefs: ["dom_bluetooth_enabled:true"]
diff --git a/tests/wpt/meta-legacy-layout/bluetooth/requestDevice/canonicalizeFilter/__dir__.ini b/tests/wpt/meta-legacy-layout/bluetooth/requestDevice/canonicalizeFilter/__dir__.ini
index 22af3fbe970..bb4133833c8 100644
--- a/tests/wpt/meta-legacy-layout/bluetooth/requestDevice/canonicalizeFilter/__dir__.ini
+++ b/tests/wpt/meta-legacy-layout/bluetooth/requestDevice/canonicalizeFilter/__dir__.ini
@@ -1,2 +1,2 @@
-prefs: ["dom.bluetooth.enabled:true"]
+prefs: ["dom_bluetooth_enabled:true"]
 disabled: "#23066"
diff --git a/tests/wpt/meta-legacy-layout/css/css-flexbox/__dir__.ini b/tests/wpt/meta-legacy-layout/css/css-flexbox/__dir__.ini
index e4af70583e1..bd1bf899085 100644
--- a/tests/wpt/meta-legacy-layout/css/css-flexbox/__dir__.ini
+++ b/tests/wpt/meta-legacy-layout/css/css-flexbox/__dir__.ini
@@ -1 +1 @@
-prefs: ["layout.columns.enabled:true", "layout.flexbox.enabled:true"]
+prefs: ["layout_columns_enabled:true", "layout_flexbox_enabled:true"]
diff --git a/tests/wpt/meta-legacy-layout/css/css-multicol/__dir__.ini b/tests/wpt/meta-legacy-layout/css/css-multicol/__dir__.ini
index 383f96c4de9..892701f1faa 100644
--- a/tests/wpt/meta-legacy-layout/css/css-multicol/__dir__.ini
+++ b/tests/wpt/meta-legacy-layout/css/css-multicol/__dir__.ini
@@ -1 +1 @@
-prefs: ["layout.columns.enabled:true"]
+prefs: ["layout_columns_enabled:true"]
diff --git a/tests/wpt/meta-legacy-layout/css/css-paint-api/__dir__.ini b/tests/wpt/meta-legacy-layout/css/css-paint-api/__dir__.ini
index 40806a19f49..ae295782025 100644
--- a/tests/wpt/meta-legacy-layout/css/css-paint-api/__dir__.ini
+++ b/tests/wpt/meta-legacy-layout/css/css-paint-api/__dir__.ini
@@ -1 +1 @@
-prefs: [dom.worklet.enabled:true, dom.worklet.timeout_ms:5000]
+prefs: [dom_worklet_enabled:true, dom_worklet_timeout_ms:5000]
diff --git a/tests/wpt/meta-legacy-layout/dom/nodes/__dir__.ini b/tests/wpt/meta-legacy-layout/dom/nodes/__dir__.ini
index 9aec2255c10..9743a9a6251 100644
--- a/tests/wpt/meta-legacy-layout/dom/nodes/__dir__.ini
+++ b/tests/wpt/meta-legacy-layout/dom/nodes/__dir__.ini
@@ -1,2 +1,2 @@
-prefs: ["dom.mutation_observer.enabled:true"]
+prefs: ["dom_mutation_observer_enabled:true"]
 
diff --git a/tests/wpt/meta-legacy-layout/gamepad/__dir__.ini b/tests/wpt/meta-legacy-layout/gamepad/__dir__.ini
index 7c5c7c7dd57..f10d7d4f48e 100644
--- a/tests/wpt/meta-legacy-layout/gamepad/__dir__.ini
+++ b/tests/wpt/meta-legacy-layout/gamepad/__dir__.ini
@@ -1 +1 @@
-prefs: [dom.gamepad.enabled:true]
+prefs: [dom_gamepad_enabled:true]
diff --git a/tests/wpt/meta-legacy-layout/html/canvas/__dir__.ini b/tests/wpt/meta-legacy-layout/html/canvas/__dir__.ini
index 03004f6efd7..e0b3c7bf146 100644
--- a/tests/wpt/meta-legacy-layout/html/canvas/__dir__.ini
+++ b/tests/wpt/meta-legacy-layout/html/canvas/__dir__.ini
@@ -1 +1 @@
-prefs: ["dom.offscreen_canvas.enabled:true"]
+prefs: ["dom_offscreen_canvas_enabled:true"]
diff --git a/tests/wpt/meta-legacy-layout/permissions/__dir__.ini b/tests/wpt/meta-legacy-layout/permissions/__dir__.ini
index dbc555f5fe3..6e0ca3e9bce 100644
--- a/tests/wpt/meta-legacy-layout/permissions/__dir__.ini
+++ b/tests/wpt/meta-legacy-layout/permissions/__dir__.ini
@@ -1 +1 @@
-prefs: ["dom.permissions.enabled:true"]
+prefs: ["dom_permissions_enabled:true"]
diff --git a/tests/wpt/meta-legacy-layout/service-workers/__dir__.ini b/tests/wpt/meta-legacy-layout/service-workers/__dir__.ini
index 263f9e73533..188c43180a1 100644
--- a/tests/wpt/meta-legacy-layout/service-workers/__dir__.ini
+++ b/tests/wpt/meta-legacy-layout/service-workers/__dir__.ini
@@ -1,2 +1,2 @@
-prefs: ["dom.serviceworker.enabled:true"]
+prefs: ["dom_serviceworker_enabled:true"]
 
diff --git a/tests/wpt/meta-legacy-layout/webvtt/__dir__.ini b/tests/wpt/meta-legacy-layout/webvtt/__dir__.ini
index a1f438d013a..69d02fac171 100644
--- a/tests/wpt/meta-legacy-layout/webvtt/__dir__.ini
+++ b/tests/wpt/meta-legacy-layout/webvtt/__dir__.ini
@@ -1,2 +1,2 @@
-prefs: ["dom.webvtt.enabled:true"]
+prefs: ["dom_webvtt_enabled:true"]
 
diff --git a/tests/wpt/meta-legacy-layout/webxr/__dir__.ini b/tests/wpt/meta-legacy-layout/webxr/__dir__.ini
index 828dff7605a..361edc79149 100644
--- a/tests/wpt/meta-legacy-layout/webxr/__dir__.ini
+++ b/tests/wpt/meta-legacy-layout/webxr/__dir__.ini
@@ -1 +1 @@
-prefs: [dom.webxr.test:true, dom.webgl2.enabled: true]
+prefs: [dom_webxr_test:true, dom_webgl2_enabled: true]
diff --git a/tests/wpt/meta/WebCryptoAPI/__dir__.ini b/tests/wpt/meta/WebCryptoAPI/__dir__.ini
index 71feefa5fb7..67f689a6cde 100644
--- a/tests/wpt/meta/WebCryptoAPI/__dir__.ini
+++ b/tests/wpt/meta/WebCryptoAPI/__dir__.ini
@@ -1 +1 @@
-prefs: [dom.crypto.subtle.enabled: true]
\ No newline at end of file
+prefs: [dom_crypto_subtle_enabled: true]
\ No newline at end of file
diff --git a/tests/wpt/meta/__dir__.ini b/tests/wpt/meta/__dir__.ini
index bb3e3d73f05..b78ab9506b3 100644
--- a/tests/wpt/meta/__dir__.ini
+++ b/tests/wpt/meta/__dir__.ini
@@ -1 +1 @@
-prefs: ["dom.imagebitmap.enabled:true", "dom.offscreen_canvas.enabled:true", "dom.shadowdom.enabled:true", "dom.xpath.enabled:true"]
+prefs: ["dom_imagebitmap_enabled:true", "dom_offscreen_canvas_enabled:true", "dom_shadowdom_enabled:true", "dom_xpath_enabled:true"]
diff --git a/tests/wpt/meta/css/css-align/__dir__.ini b/tests/wpt/meta/css/css-align/__dir__.ini
index e4af70583e1..bd1bf899085 100644
--- a/tests/wpt/meta/css/css-align/__dir__.ini
+++ b/tests/wpt/meta/css/css-align/__dir__.ini
@@ -1 +1 @@
-prefs: ["layout.columns.enabled:true", "layout.flexbox.enabled:true"]
+prefs: ["layout_columns_enabled:true", "layout_flexbox_enabled:true"]
diff --git a/tests/wpt/meta/css/css-flexbox/__dir__.ini b/tests/wpt/meta/css/css-flexbox/__dir__.ini
index e4af70583e1..bd1bf899085 100644
--- a/tests/wpt/meta/css/css-flexbox/__dir__.ini
+++ b/tests/wpt/meta/css/css-flexbox/__dir__.ini
@@ -1 +1 @@
-prefs: ["layout.columns.enabled:true", "layout.flexbox.enabled:true"]
+prefs: ["layout_columns_enabled:true", "layout_flexbox_enabled:true"]
diff --git a/tests/wpt/meta/css/css-grid/__dir__.ini b/tests/wpt/meta/css/css-grid/__dir__.ini
index 7d65365a765..745da0bac0a 100644
--- a/tests/wpt/meta/css/css-grid/__dir__.ini
+++ b/tests/wpt/meta/css/css-grid/__dir__.ini
@@ -1 +1 @@
-prefs: ["layout.columns.enabled:true", "layout.flexbox.enabled:true", "layout.grid.enabled:true"]
+prefs: ["layout_columns_enabled:true", "layout_flexbox_enabled:true", "layout_grid_enabled:true"]
diff --git a/tests/wpt/meta/gamepad/__dir__.ini b/tests/wpt/meta/gamepad/__dir__.ini
index 18827c1dbe2..925bd35d947 100644
--- a/tests/wpt/meta/gamepad/__dir__.ini
+++ b/tests/wpt/meta/gamepad/__dir__.ini
@@ -1 +1 @@
-prefs: [dom.gamepad.enabled: true]
\ No newline at end of file
+prefs: [dom_gamepad_enabled: true]
\ No newline at end of file
diff --git a/tests/wpt/meta/resize-observer/__dir__.ini b/tests/wpt/meta/resize-observer/__dir__.ini
index 4d4f1e646b2..19c126482f0 100644
--- a/tests/wpt/meta/resize-observer/__dir__.ini
+++ b/tests/wpt/meta/resize-observer/__dir__.ini
@@ -1 +1 @@
-prefs: ["dom.resize_observer.enabled:true"]
+prefs: ["dom_resize_observer_enabled:true"]
diff --git a/tests/wpt/meta/webxr/__dir__.ini b/tests/wpt/meta/webxr/__dir__.ini
index 16c2a8593c1..2e3a5cdb659 100644
--- a/tests/wpt/meta/webxr/__dir__.ini
+++ b/tests/wpt/meta/webxr/__dir__.ini
@@ -1 +1 @@
-prefs: [dom.webxr.test: true, dom.webgl2.enabled: true, dom.webxr.layers.enabled: true]
\ No newline at end of file
+prefs: [dom_webxr_test: true, dom_webgl2_enabled: true, dom_webxr_layers_enabled: true]
\ No newline at end of file
diff --git a/tests/wpt/mozilla/meta-legacy-layout/bluetooth/__dir__.ini b/tests/wpt/mozilla/meta-legacy-layout/bluetooth/__dir__.ini
index c95b7c11c1d..1afc2794872 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/bluetooth/__dir__.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/bluetooth/__dir__.ini
@@ -1 +1 @@
-prefs: [dom.bluetooth.enabled:true, dom.bluetooth.testing.enabled:true, dom.permissions.testing.allowed_in_nonsecure_contexts:true]
+prefs: [dom_bluetooth_enabled:true, dom_bluetooth_testing_enabled:true, dom_permissions_testing_allowed_in_nonsecure_contexts:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/css/animations/__dir__.ini b/tests/wpt/mozilla/meta-legacy-layout/css/animations/__dir__.ini
index 696581b4a4a..f66ed2ce1a5 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/css/animations/__dir__.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/css/animations/__dir__.ini
@@ -1,2 +1,2 @@
-prefs: ["layout.animations.test.enabled:true",
-        "dom.testbinding.enabled:true"]
+prefs: ["layout_animations_test_enabled:true",
+        "dom_testbinding_enabled:true"]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/css/animations/animation-events.html.ini b/tests/wpt/mozilla/meta-legacy-layout/css/animations/animation-events.html.ini
index 33f08914f30..e0b3b5f6997 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/css/animations/animation-events.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/css/animations/animation-events.html.ini
@@ -1,2 +1,2 @@
-prefs: ["layout.animations.test.enabled:false",
-        "dom.testbinding.enabled:false"]
+prefs: ["layout_animations_test_enabled:false",
+        "dom_testbinding_enabled:false"]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/css/animations/transition-events.html.ini b/tests/wpt/mozilla/meta-legacy-layout/css/animations/transition-events.html.ini
index f53fd6a5050..3e398039c00 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/css/animations/transition-events.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/css/animations/transition-events.html.ini
@@ -1,3 +1,3 @@
-prefs: ["layout.animations.test.enabled:false",
-        "dom.testbinding.enabled:false"]
+prefs: ["layout_animations_test_enabled:false",
+        "dom_testbinding_enabled:false"]
 
diff --git a/tests/wpt/mozilla/meta-legacy-layout/css/direction_style_caching.html.ini b/tests/wpt/mozilla/meta-legacy-layout/css/direction_style_caching.html.ini
index b04e9dc858f..02119ac9454 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/css/direction_style_caching.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/css/direction_style_caching.html.ini
@@ -1,3 +1,3 @@
-prefs: [layout.threads:1]
+prefs: [layout_threads:1]
 [direction_style_caching.html]
   type: reftest
diff --git a/tests/wpt/mozilla/meta-legacy-layout/css/iframe/size_attributes_vertical_writing_mode.html.ini b/tests/wpt/mozilla/meta-legacy-layout/css/iframe/size_attributes_vertical_writing_mode.html.ini
index b7fd0e36dd6..52fb0568645 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/css/iframe/size_attributes_vertical_writing_mode.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/css/iframe/size_attributes_vertical_writing_mode.html.ini
@@ -1,3 +1,3 @@
-prefs: [layout.writing-mode.enabled:true]
+prefs: [layout_writing_mode_enabled:true]
 [size_attributes_vertical_writing_mode.html]
   type: reftest
diff --git a/tests/wpt/mozilla/meta-legacy-layout/css/vertical-lr-blocks.html.ini b/tests/wpt/mozilla/meta-legacy-layout/css/vertical-lr-blocks.html.ini
index 2858c27f6ed..4710d41093f 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/css/vertical-lr-blocks.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/css/vertical-lr-blocks.html.ini
@@ -1,4 +1,4 @@
-prefs: [layout.writing-mode.enabled:true]
+prefs: [layout_writing_mode_enabled:true]
 [vertical-lr-blocks.html]
   type: reftest
   expected: FAIL
diff --git a/tests/wpt/mozilla/meta-legacy-layout/css/writing-mode_change_display.html.ini b/tests/wpt/mozilla/meta-legacy-layout/css/writing-mode_change_display.html.ini
index 15717811207..a1b4bf67748 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/css/writing-mode_change_display.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/css/writing-mode_change_display.html.ini
@@ -1,3 +1,3 @@
-prefs: [layout.writing-mode.enabled:true]
+prefs: [layout_writing_mode_enabled:true]
 [writing-mode_change_display.html]
   type: testharness
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/FileAPI/blob_url_upload.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/FileAPI/blob_url_upload.html.ini
index 6ad257ede65..bc735bc38a2 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/FileAPI/blob_url_upload.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/FileAPI/blob_url_upload.html.ini
@@ -1,3 +1,3 @@
 [blob_url_upload.html]
   type: reftest
-  prefs: [dom.testing.htmlinputelement.select_files.enabled:true]
+  prefs: [dom_testing_html_input_element_select_files_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/FileAPI/file-select.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/FileAPI/file-select.html.ini
index b047e230d99..318e272941d 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/FileAPI/file-select.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/FileAPI/file-select.html.ini
@@ -1,3 +1,3 @@
 [file-select.html]
   type: testharness
-  prefs: [dom.testing.htmlinputelement.select_files.enabled:true]
+  prefs: [dom_testing_html_input_element_select_files_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/FileAPI/file-upload.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/FileAPI/file-upload.html.ini
index f3715f47bf9..26ffa70324d 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/FileAPI/file-upload.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/FileAPI/file-upload.html.ini
@@ -1,3 +1,3 @@
 [file-upload.html]
   type: testharness
-  prefs: [dom.testing.htmlinputelement.select_files.enabled:true]
+  prefs: [dom_testing_html_input_element_select_files_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/activation.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/activation.html.ini
index e7b9f2349c3..96bb5bc6f86 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/activation.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/activation.html.ini
@@ -1,3 +1,3 @@
 [activation.html]
   type: testharness
-  prefs: [dom.testing.element.activation.enabled:true]
+  prefs: [dom_testing_element_activation_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/binding_keyword.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/binding_keyword.html.ini
index 4b7bda760f0..2f27eb85244 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/binding_keyword.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/binding_keyword.html.ini
@@ -1,3 +1,3 @@
 [binding_keyword.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/calc.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/calc.html.ini
index e962fd6bbd5..c69d9c8e4ff 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/calc.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/calc.html.ini
@@ -1,3 +1,3 @@
 [calc.html]
   type: testharness
-  prefs: [layout.columns.enabled:true]
+  prefs: [layout_columns_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/codegen_unions.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/codegen_unions.html.ini
index 6a8744c375d..1466ea82c0d 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/codegen_unions.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/codegen_unions.html.ini
@@ -1,3 +1,3 @@
 [codegen_unions.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/custom_auto_rooter.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/custom_auto_rooter.html.ini
index def641a83ba..4d3562b0c1c 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/custom_auto_rooter.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/custom_auto_rooter.html.ini
@@ -1,3 +1,3 @@
 [custom_auto_rooter.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/dictionary_to_jsval.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/dictionary_to_jsval.html.ini
index 850a38abfbc..ff7a331d22b 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/dictionary_to_jsval.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/dictionary_to_jsval.html.ini
@@ -1,2 +1,2 @@
 [dictionary_to_jsval.html]
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/exceptionToRejection.any.js.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/exceptionToRejection.any.js.ini
index 7d7e4d9cdc7..ee2780a9a5a 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/exceptionToRejection.any.js.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/exceptionToRejection.any.js.ini
@@ -1,7 +1,7 @@
 [exceptionToRejection.any.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
 
 [exceptionToRejection.any.worker.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
\ No newline at end of file
+  prefs: [dom_testbinding_enabled:true]
\ No newline at end of file
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/fullscreen/reftests/__dir__.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/fullscreen/reftests/__dir__.ini
index d2259b78e4e..91f58deb0c0 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/fullscreen/reftests/__dir__.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/fullscreen/reftests/__dir__.ini
@@ -1 +1 @@
-prefs: ["dom.fullscreen.test:true"]
+prefs: ["dom_fullscreen_test:true"]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/globals/entry.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/globals/entry.html.ini
index 52b122bc295..fe0c41210ac 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/globals/entry.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/globals/entry.html.ini
@@ -1,3 +1,3 @@
 [entry.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/globals/entry.worker.js.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/globals/entry.worker.js.ini
index 2205984347e..29638929d3f 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/globals/entry.worker.js.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/globals/entry.worker.js.ini
@@ -1,3 +1,3 @@
 [entry.worker.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/http-cache.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/http-cache.html.ini
index d52addb7abc..e14018c7235 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/http-cache.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/http-cache.html.ini
@@ -1,6 +1,6 @@
 [http-cache.html]
   type: testharness
-  prefs: [network.http-cache.disabled:true]
+  prefs: [network_http_cache_disabled:true]
   [HTTP cache, when disabled, does not cache a 200 response.]
     expected: FAIL
 
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/interface_member_exposed.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/interface_member_exposed.html.ini
index cb010511bf7..cfd83349642 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/interface_member_exposed.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/interface_member_exposed.html.ini
@@ -1,3 +1,3 @@
 [interface_member_exposed.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true, dom.testbinding.prefcontrolled2.enabled:true]
+  prefs: [dom_testbinding_enabled:true, dom_testbinding_prefcontrolled2_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/interfaces.https.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/interfaces.https.html.ini
index 32a9f966eeb..605489ac6bc 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/interfaces.https.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/interfaces.https.html.ini
@@ -1 +1 @@
-prefs: [dom.webxr.test: false]
\ No newline at end of file
+prefs: [dom_webxr_test: false]
\ No newline at end of file
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/iterable.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/iterable.html.ini
index 2316a8b3984..23e8bef9480 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/iterable.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/iterable.html.ini
@@ -1,3 +1,3 @@
 [iterable.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/like.any.js.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/like.any.js.ini
index 626c7c904f2..a4040cad82c 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/like.any.js.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/like.any.js.ini
@@ -1,6 +1,6 @@
 [like.any.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
   [Test defaulting arguments on setlike to undefined]
     expected: FAIL
 
@@ -12,7 +12,7 @@
 
 [like.any.worker.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
   [Test defaulting arguments on setlike to undefined]
     expected: FAIL
 
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/media_query_list_gc.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/media_query_list_gc.html.ini
index e30744b586d..f4ee735be13 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/media_query_list_gc.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/media_query_list_gc.html.ini
@@ -1 +1 @@
-prefs: ["dom.servo_helpers.enabled:true"]
+prefs: ["dom_servo_helpers_enabled:true"]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/microdata/__dir__.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/microdata/__dir__.ini
index f199618497d..b68814a2034 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/microdata/__dir__.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/microdata/__dir__.ini
@@ -1 +1 @@
-prefs: ["dom.microdata.testing.enabled:true"]
+prefs: ["dom_microdata_testing_enabled:true"]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/ns.any.js.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/ns.any.js.ini
index 1028c1162dd..749cda0d24e 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/ns.any.js.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/ns.any.js.ini
@@ -1,7 +1,7 @@
 [ns.any.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
 
 [ns.any.worker.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/overload_dict.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/overload_dict.html.ini
index 646813bf83c..12d91fea367 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/overload_dict.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/overload_dict.html.ini
@@ -1,3 +1,3 @@
 [overload_dict.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/partial_shadow_dom.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/partial_shadow_dom.html.ini
index 570ed139ec1..5e99741dc6f 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/partial_shadow_dom.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/partial_shadow_dom.html.ini
@@ -1,4 +1,4 @@
 [partial_shadow_dom.html]
-  prefs: [dom.shadowdom.enabled:true]
+  prefs: [dom_shadowdom_enabled:true]
   [partial_shadow_dom]
     expected: FAIL
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/partial_shadow_dom_layout_style.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/partial_shadow_dom_layout_style.html.ini
index 6612e2fb467..ebc51a2e59d 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/partial_shadow_dom_layout_style.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/partial_shadow_dom_layout_style.html.ini
@@ -1,2 +1,2 @@
 [partial_shadow_dom_layout_style.html]
-  prefs: [dom.shadowdom.enabled:true]
+  prefs: [dom_shadowdom_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/preferences.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/preferences.html.ini
index 83de4dd69cd..986d3d09917 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/preferences.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/preferences.html.ini
@@ -1,3 +1,3 @@
 [preferences.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true, dom.testbinding.preference_value.falsy:false, dom.testbinding.preference_value.truthy:true, dom.testbinding.preference_value.string_empty:, dom.testbinding.preference_value.string_test:test, dom.testbinding.preference_value.space_string_test:test1 test2, dom.testbinding.preference_value.quote_string_test:"test1 test2"]
+  prefs: [dom_testbinding_enabled:true, dom_testbinding_preference_value_falsy:false, dom_testbinding_preference_value_truthy:true, dom_testbinding_preference_value_string_empty:, dom_testbinding_preference_value_string_test:test, dom_testbinding_preference_value_space_string_test:test1 test2, dom_testbinding_preference_value_quote_string_test:"test1 test2"]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/promise.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/promise.html.ini
index e5ac0e78cd9..85f32f8d2a1 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/promise.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/promise.html.ini
@@ -1,6 +1,6 @@
 [promise.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
   [Native promise from async callback can be resolved]
     expected: FAIL
 
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/prototypes.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/prototypes.html.ini
index e30744b586d..f4ee735be13 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/prototypes.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/prototypes.html.ini
@@ -1 +1 @@
-prefs: ["dom.servo_helpers.enabled:true"]
+prefs: ["dom_servo_helpers_enabled:true"]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/sequence-hole.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/sequence-hole.html.ini
index e3da43f8d3b..3e1cd2169c8 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/sequence-hole.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/sequence-hole.html.ini
@@ -1,3 +1,3 @@
 [sequence-hole.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/service-workers/__dir__.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/service-workers/__dir__.ini
index e4456cb4756..5baa980a233 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/service-workers/__dir__.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/service-workers/__dir__.ini
@@ -1 +1 @@
-prefs: ["dom.serviceworker.enabled:true"]
+prefs: ["dom_serviceworker_enabled:true"]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/sigsegv.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/sigsegv.html.ini
index 63ad264be81..4f116d7c3f8 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/sigsegv.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/sigsegv.html.ini
@@ -1,4 +1,4 @@
 [sigsegv.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true, dom.testable_crash.enabled:true]
+  prefs: [dom_testbinding_enabled:true, dom_testable_crash_enabled:true]
   expected: CRASH
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/svg/svg.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/svg/svg.html.ini
index 2f440fde23f..6d1a5d0b3ee 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/svg/svg.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/svg/svg.html.ini
@@ -1,3 +1,3 @@
 [svg.html]
   type: reftest
-  prefs: [dom.svg.enabled:true]
+  prefs: [dom_svg_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/trace_null.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/trace_null.html.ini
index e30744b586d..f4ee735be13 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/trace_null.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/trace_null.html.ini
@@ -1 +1 @@
-prefs: ["dom.servo_helpers.enabled:true"]
+prefs: ["dom_servo_helpers_enabled:true"]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/transitionend_safety.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/transitionend_safety.html.ini
index e30744b586d..f4ee735be13 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/transitionend_safety.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/transitionend_safety.html.ini
@@ -1 +1 @@
-prefs: ["dom.servo_helpers.enabled:true"]
+prefs: ["dom_servo_helpers_enabled:true"]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/variadic-interface.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/variadic-interface.html.ini
index f21720b9363..ac12007d5e1 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/variadic-interface.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/variadic-interface.html.ini
@@ -1,3 +1,3 @@
 [variadic-interface.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/video_poster_frame.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/video_poster_frame.html.ini
index 300efbf7350..7594b72f4c4 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/video_poster_frame.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/video_poster_frame.html.ini
@@ -1,2 +1,2 @@
 [video_poster_frame.html]
-  prefs: [media.testing.enabled:true]
+  prefs: [media_testing_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/weakref.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/weakref.html.ini
index 8faf1a9b047..17ca8b55091 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/weakref.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/weakref.html.ini
@@ -1,3 +1,3 @@
 [weakref.html]
   type: testharness
-  prefs: ["dom.testbinding.enabled:true", "dom.servo_helpers.enabled:true"]
+  prefs: ["dom_testbinding_enabled:true", "dom_servo_helpers_enabled:true"]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/webgl/context_creation_error.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/webgl/context_creation_error.html.ini
index cce1d7c3a5f..67020650ae9 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/webgl/context_creation_error.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/webgl/context_creation_error.html.ini
@@ -1,3 +1,3 @@
 [context_creation_error.html]
   type: testharness
-  prefs: [webgl.testing.context_creation_error:true]
+  prefs: [webgl_testing_context_creation_error:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/window_performance_topLevelDomComplete.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/window_performance_topLevelDomComplete.html.ini
index ac65905cb3d..5beb7dc6158 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/window_performance_topLevelDomComplete.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/window_performance_topLevelDomComplete.html.ini
@@ -1,3 +1,3 @@
 [window_performance_topLevelDomComplete.html]
   type: testharness
-  prefs: [dom.testperf.enabled:true]
+  prefs: [dom_testperf_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/worklets/__dir__.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/worklets/__dir__.ini
index c000a50cb3b..1d33f917a21 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/worklets/__dir__.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/worklets/__dir__.ini
@@ -1 +1 @@
-prefs: [dom.worklet.enabled:true,dom.worklet.blockingsleep.enabled:true,dom.worklet.timeout_ms:5000]
+prefs: [dom_worklet_enabled:true,dom_worklet_blockingsleep_enabled:true,dom_worklet_timeout_ms:5000]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/worklets/test_paint_worklet_timeout.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/worklets/test_paint_worklet_timeout.html.ini
index bc2b728c300..d2b3d5537ff 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/worklets/test_paint_worklet_timeout.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/worklets/test_paint_worklet_timeout.html.ini
@@ -1,4 +1,4 @@
 [test_paint_worklet_timeout.html]
   type: testharness
-  prefs: [dom.worklet.timeout_ms:10]
+  prefs: [dom_worklet_timeout_ms:10]
   expected: PASS
diff --git a/tests/wpt/mozilla/meta-legacy-layout/mozilla/worklets/test_worklet.html.ini b/tests/wpt/mozilla/meta-legacy-layout/mozilla/worklets/test_worklet.html.ini
index 37762a513dd..45a182aece1 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/mozilla/worklets/test_worklet.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/mozilla/worklets/test_worklet.html.ini
@@ -1,3 +1,3 @@
 [test_worklet.html]
   type: testharness
-  prefs: [dom.worklet.testing.enabled:true]
+  prefs: [dom_worklet_testing_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/webxr/__dir__.ini b/tests/wpt/mozilla/meta-legacy-layout/webxr/__dir__.ini
index fe96a649902..a36827bd1d6 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/webxr/__dir__.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/webxr/__dir__.ini
@@ -1,2 +1,2 @@
-prefs: [dom.webxr.enabled:true, dom.webxr.test:true]
+prefs: [dom_webxr_enabled:true, dom_webxr_test:true]
 
diff --git a/tests/wpt/mozilla/meta-legacy-layout/webxr/layerevents.https.html.ini b/tests/wpt/mozilla/meta-legacy-layout/webxr/layerevents.https.html.ini
index 72e1e4fc0b2..dde4edb26a1 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/webxr/layerevents.https.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/webxr/layerevents.https.html.ini
@@ -1 +1 @@
-prefs: [dom.webxr.layers.enabled:true]
+prefs: [dom_webxr_layers_enabled:true]
diff --git a/tests/wpt/mozilla/meta-legacy-layout/webxr/layers.https.html.ini b/tests/wpt/mozilla/meta-legacy-layout/webxr/layers.https.html.ini
index 86b374c7e4b..3ebe90ed370 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/webxr/layers.https.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/webxr/layers.https.html.ini
@@ -1,4 +1,4 @@
-prefs: [dom.webxr.layers.enabled:true]
+prefs: [dom_webxr_layers_enabled:true]
 [layers.https.html]
   [layers]
     expected: FAIL
diff --git a/tests/wpt/mozilla/meta-legacy-layout/webxr/sessionavailable.https.html.ini b/tests/wpt/mozilla/meta-legacy-layout/webxr/sessionavailable.https.html.ini
index 8bf6ba72fd8..53c832736b7 100644
--- a/tests/wpt/mozilla/meta-legacy-layout/webxr/sessionavailable.https.html.ini
+++ b/tests/wpt/mozilla/meta-legacy-layout/webxr/sessionavailable.https.html.ini
@@ -1,2 +1,2 @@
-prefs: [dom.webxr.sessionavailable:true]
+prefs: [dom_webxr_sessionavailable:true]
 
diff --git a/tests/wpt/mozilla/meta/css/animations/__dir__.ini b/tests/wpt/mozilla/meta/css/animations/__dir__.ini
index 696581b4a4a..f66ed2ce1a5 100644
--- a/tests/wpt/mozilla/meta/css/animations/__dir__.ini
+++ b/tests/wpt/mozilla/meta/css/animations/__dir__.ini
@@ -1,2 +1,2 @@
-prefs: ["layout.animations.test.enabled:true",
-        "dom.testbinding.enabled:true"]
+prefs: ["layout_animations_test_enabled:true",
+        "dom_testbinding_enabled:true"]
diff --git a/tests/wpt/mozilla/meta/css/animations/animation-events.html.ini b/tests/wpt/mozilla/meta/css/animations/animation-events.html.ini
index 33f08914f30..e0b3b5f6997 100644
--- a/tests/wpt/mozilla/meta/css/animations/animation-events.html.ini
+++ b/tests/wpt/mozilla/meta/css/animations/animation-events.html.ini
@@ -1,2 +1,2 @@
-prefs: ["layout.animations.test.enabled:false",
-        "dom.testbinding.enabled:false"]
+prefs: ["layout_animations_test_enabled:false",
+        "dom_testbinding_enabled:false"]
diff --git a/tests/wpt/mozilla/meta/css/animations/transition-events.html.ini b/tests/wpt/mozilla/meta/css/animations/transition-events.html.ini
index f53fd6a5050..3e398039c00 100644
--- a/tests/wpt/mozilla/meta/css/animations/transition-events.html.ini
+++ b/tests/wpt/mozilla/meta/css/animations/transition-events.html.ini
@@ -1,3 +1,3 @@
-prefs: ["layout.animations.test.enabled:false",
-        "dom.testbinding.enabled:false"]
+prefs: ["layout_animations_test_enabled:false",
+        "dom_testbinding_enabled:false"]
 
diff --git a/tests/wpt/mozilla/meta/css/flex_align_content_stretch_subpixel.html.ini b/tests/wpt/mozilla/meta/css/flex_align_content_stretch_subpixel.html.ini
index 9984b470f38..7a21695e3d5 100644
--- a/tests/wpt/mozilla/meta/css/flex_align_content_stretch_subpixel.html.ini
+++ b/tests/wpt/mozilla/meta/css/flex_align_content_stretch_subpixel.html.ini
@@ -1,2 +1,2 @@
 [flex_align_content_stretch_subpixel.html]
-  prefs: ["layout.flexbox.enabled:true"]
+  prefs: ["layout_flexbox_enabled:true"]
diff --git a/tests/wpt/mozilla/meta/mozilla/DOMParser-parseFromString.html.ini b/tests/wpt/mozilla/meta/mozilla/DOMParser-parseFromString.html.ini
index 6fb710b0407..4ea07616469 100644
--- a/tests/wpt/mozilla/meta/mozilla/DOMParser-parseFromString.html.ini
+++ b/tests/wpt/mozilla/meta/mozilla/DOMParser-parseFromString.html.ini
@@ -1,2 +1,2 @@
 [DOMParser-parseFromString.html]
-  prefs: ["dom.servoparser.async_html_tokenizer.enabled:true"]
+  prefs: ["dom_servoparser_async_html_tokenizer_enabled:true"]
diff --git a/tests/wpt/mozilla/meta/mozilla/dictionary_to_jsval.html.ini b/tests/wpt/mozilla/meta/mozilla/dictionary_to_jsval.html.ini
index 850a38abfbc..ff7a331d22b 100644
--- a/tests/wpt/mozilla/meta/mozilla/dictionary_to_jsval.html.ini
+++ b/tests/wpt/mozilla/meta/mozilla/dictionary_to_jsval.html.ini
@@ -1,2 +1,2 @@
 [dictionary_to_jsval.html]
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
diff --git a/tests/wpt/mozilla/meta/mozilla/exceptionToRejection.any.js.ini b/tests/wpt/mozilla/meta/mozilla/exceptionToRejection.any.js.ini
index 7d7e4d9cdc7..ee2780a9a5a 100644
--- a/tests/wpt/mozilla/meta/mozilla/exceptionToRejection.any.js.ini
+++ b/tests/wpt/mozilla/meta/mozilla/exceptionToRejection.any.js.ini
@@ -1,7 +1,7 @@
 [exceptionToRejection.any.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
 
 [exceptionToRejection.any.worker.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
\ No newline at end of file
+  prefs: [dom_testbinding_enabled:true]
\ No newline at end of file
diff --git a/tests/wpt/mozilla/meta/mozilla/interfaces.https.html.ini b/tests/wpt/mozilla/meta/mozilla/interfaces.https.html.ini
index 32a9f966eeb..605489ac6bc 100644
--- a/tests/wpt/mozilla/meta/mozilla/interfaces.https.html.ini
+++ b/tests/wpt/mozilla/meta/mozilla/interfaces.https.html.ini
@@ -1 +1 @@
-prefs: [dom.webxr.test: false]
\ No newline at end of file
+prefs: [dom_webxr_test: false]
\ No newline at end of file
diff --git a/tests/wpt/mozilla/meta/mozilla/like.any.js.ini b/tests/wpt/mozilla/meta/mozilla/like.any.js.ini
index 626c7c904f2..a4040cad82c 100644
--- a/tests/wpt/mozilla/meta/mozilla/like.any.js.ini
+++ b/tests/wpt/mozilla/meta/mozilla/like.any.js.ini
@@ -1,6 +1,6 @@
 [like.any.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
   [Test defaulting arguments on setlike to undefined]
     expected: FAIL
 
@@ -12,7 +12,7 @@
 
 [like.any.worker.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
   [Test defaulting arguments on setlike to undefined]
     expected: FAIL
 
diff --git a/tests/wpt/mozilla/meta/mozilla/media_query_list_gc.html.ini b/tests/wpt/mozilla/meta/mozilla/media_query_list_gc.html.ini
index e30744b586d..f4ee735be13 100644
--- a/tests/wpt/mozilla/meta/mozilla/media_query_list_gc.html.ini
+++ b/tests/wpt/mozilla/meta/mozilla/media_query_list_gc.html.ini
@@ -1 +1 @@
-prefs: ["dom.servo_helpers.enabled:true"]
+prefs: ["dom_servo_helpers_enabled:true"]
diff --git a/tests/wpt/mozilla/meta/mozilla/ns.any.js.ini b/tests/wpt/mozilla/meta/mozilla/ns.any.js.ini
index 1028c1162dd..749cda0d24e 100644
--- a/tests/wpt/mozilla/meta/mozilla/ns.any.js.ini
+++ b/tests/wpt/mozilla/meta/mozilla/ns.any.js.ini
@@ -1,7 +1,7 @@
 [ns.any.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
 
 [ns.any.worker.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
diff --git a/tests/wpt/mozilla/meta/mozilla/overload_dict.html.ini b/tests/wpt/mozilla/meta/mozilla/overload_dict.html.ini
index 646813bf83c..12d91fea367 100644
--- a/tests/wpt/mozilla/meta/mozilla/overload_dict.html.ini
+++ b/tests/wpt/mozilla/meta/mozilla/overload_dict.html.ini
@@ -1,3 +1,3 @@
 [overload_dict.html]
   type: testharness
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
diff --git a/tests/wpt/mozilla/meta/mozilla/prototypes.html.ini b/tests/wpt/mozilla/meta/mozilla/prototypes.html.ini
index e30744b586d..f4ee735be13 100644
--- a/tests/wpt/mozilla/meta/mozilla/prototypes.html.ini
+++ b/tests/wpt/mozilla/meta/mozilla/prototypes.html.ini
@@ -1 +1 @@
-prefs: ["dom.servo_helpers.enabled:true"]
+prefs: ["dom_servo_helpers_enabled:true"]
diff --git a/tests/wpt/mozilla/meta/mozilla/sequence-hole.html.ini b/tests/wpt/mozilla/meta/mozilla/sequence-hole.html.ini
index a7798c9c3c3..27e9f2f853f 100644
--- a/tests/wpt/mozilla/meta/mozilla/sequence-hole.html.ini
+++ b/tests/wpt/mozilla/meta/mozilla/sequence-hole.html.ini
@@ -1,2 +1,2 @@
 [sequence-hole.html]
-  prefs: [dom.testbinding.enabled:true]
+  prefs: [dom_testbinding_enabled:true]
diff --git a/tests/wpt/mozilla/meta/mozilla/trace_null.html.ini b/tests/wpt/mozilla/meta/mozilla/trace_null.html.ini
index e30744b586d..f4ee735be13 100644
--- a/tests/wpt/mozilla/meta/mozilla/trace_null.html.ini
+++ b/tests/wpt/mozilla/meta/mozilla/trace_null.html.ini
@@ -1 +1 @@
-prefs: ["dom.servo_helpers.enabled:true"]
+prefs: ["dom_servo_helpers_enabled:true"]
diff --git a/tests/wpt/mozilla/meta/mozilla/transitionend_safety.html.ini b/tests/wpt/mozilla/meta/mozilla/transitionend_safety.html.ini
index e30744b586d..f4ee735be13 100644
--- a/tests/wpt/mozilla/meta/mozilla/transitionend_safety.html.ini
+++ b/tests/wpt/mozilla/meta/mozilla/transitionend_safety.html.ini
@@ -1 +1 @@
-prefs: ["dom.servo_helpers.enabled:true"]
+prefs: ["dom_servo_helpers_enabled:true"]
diff --git a/tests/wpt/mozilla/meta/mozilla/weakref.html.ini b/tests/wpt/mozilla/meta/mozilla/weakref.html.ini
index 8faf1a9b047..17ca8b55091 100644
--- a/tests/wpt/mozilla/meta/mozilla/weakref.html.ini
+++ b/tests/wpt/mozilla/meta/mozilla/weakref.html.ini
@@ -1,3 +1,3 @@
 [weakref.html]
   type: testharness
-  prefs: ["dom.testbinding.enabled:true", "dom.servo_helpers.enabled:true"]
+  prefs: ["dom_testbinding_enabled:true", "dom_servo_helpers_enabled:true"]
diff --git a/tests/wpt/webgl/meta-legacy-layout/conformance/__dir__.ini b/tests/wpt/webgl/meta-legacy-layout/conformance/__dir__.ini
index 268ced65042..b1c646726d8 100644
--- a/tests/wpt/webgl/meta-legacy-layout/conformance/__dir__.ini
+++ b/tests/wpt/webgl/meta-legacy-layout/conformance/__dir__.ini
@@ -1 +1 @@
-prefs: ["dom.offscreen_canvas.enabled:true","dom.imagebitmap.enabled:true"]
+prefs: ["dom_offscreen_canvas_enabled:true","dom_imagebitmap_enabled:true"]
diff --git a/tests/wpt/webgl/meta-legacy-layout/conformance2/__dir__.ini b/tests/wpt/webgl/meta-legacy-layout/conformance2/__dir__.ini
index 2540f857c82..148295a0104 100644
--- a/tests/wpt/webgl/meta-legacy-layout/conformance2/__dir__.ini
+++ b/tests/wpt/webgl/meta-legacy-layout/conformance2/__dir__.ini
@@ -1,2 +1,2 @@
-prefs: ["dom.webgl2.enabled:true","dom.offscreen_canvas.enabled:true","dom.imagebitmap.enabled:true"]
+prefs: ["dom_webgl2_enabled:true","dom_offscreen_canvas_enabled:true","dom_imagebitmap_enabled:true"]
 
diff --git a/tests/wpt/webgl/meta-legacy-layout/conformance2/offscreencanvas/__dir__.ini b/tests/wpt/webgl/meta-legacy-layout/conformance2/offscreencanvas/__dir__.ini
index 03004f6efd7..e0b3c7bf146 100644
--- a/tests/wpt/webgl/meta-legacy-layout/conformance2/offscreencanvas/__dir__.ini
+++ b/tests/wpt/webgl/meta-legacy-layout/conformance2/offscreencanvas/__dir__.ini
@@ -1 +1 @@
-prefs: ["dom.offscreen_canvas.enabled:true"]
+prefs: ["dom_offscreen_canvas_enabled:true"]
diff --git a/tests/wpt/webgl/meta/__dir__.ini b/tests/wpt/webgl/meta/__dir__.ini
index 8ff113eb2cb..f2f09393f27 100644
--- a/tests/wpt/webgl/meta/__dir__.ini
+++ b/tests/wpt/webgl/meta/__dir__.ini
@@ -1 +1 @@
-prefs: ["dom.offscreen_canvas.enabled:true", "dom.imagebitmap.enabled:true", "dom.webgl2.enabled:true"]
+prefs: ["dom_offscreen_canvas_enabled:true", "dom_imagebitmap_enabled:true", "dom_webgl2_enabled:true"]
diff --git a/tests/wpt/webgl/meta/conformance2/offscreencanvas/__dir__.ini b/tests/wpt/webgl/meta/conformance2/offscreencanvas/__dir__.ini
index 03004f6efd7..e0b3c7bf146 100644
--- a/tests/wpt/webgl/meta/conformance2/offscreencanvas/__dir__.ini
+++ b/tests/wpt/webgl/meta/conformance2/offscreencanvas/__dir__.ini
@@ -1 +1 @@
-prefs: ["dom.offscreen_canvas.enabled:true"]
+prefs: ["dom_offscreen_canvas_enabled:true"]
diff --git a/tests/wpt/webgpu/meta/__dir__.ini b/tests/wpt/webgpu/meta/__dir__.ini
index bb05019d943..7992a6f4879 100644
--- a/tests/wpt/webgpu/meta/__dir__.ini
+++ b/tests/wpt/webgpu/meta/__dir__.ini
@@ -1 +1 @@
-prefs: ["dom.webgpu.enabled:true"]
+prefs: ["dom_webgpu_enabled:true"]