Auto merge of #22353 - jdm:runtime-parent, r=nox

Update rust-mozjs

These changes adjust our uses of the rust-mozjs APIs to accommodate the changes in https://github.com/servo/rust-mozjs/pull/450.

---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #22342.
- [x] There are tests for these changes

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---
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11 files changed, 65 insertions, 35 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 63671acf85e..6120f957998 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2308,7 +2308,7 @@ dependencies = [
  "hyper 0.12.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "hyper_serde 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "keyboard-types 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "mozjs 0.9.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "mozjs 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "selectors 0.21.0",
  "serde 1.0.80 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_bytes 0.10.4 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2532,7 +2532,7 @@ dependencies = [
 
 [[package]]
 name = "mozjs"
-version = "0.9.5"
+version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cc 1.0.18 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3295,7 +3295,7 @@ dependencies = [
  "mime_guess 2.0.0-alpha.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "mitochondria 1.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "mozangle 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "mozjs 0.9.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "mozjs 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "msg 0.0.1",
  "net_traits 0.0.1",
  "num-traits 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -5064,7 +5064,7 @@ dependencies = [
 "checksum miow 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "8c1f2f3b1cf331de6896aabf6e9d55dca90356cc9960cca7eaaf408a355ae919"
 "checksum mitochondria 1.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "9de3eca27871df31c33b807f834b94ef7d000956f57aa25c5aed9c5f0aae8f6f"
 "checksum mozangle 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)" = "45a8a18a41cfab0fde25cc2f43ea89064d211a0fbb33225b8ff93ab20406e0e7"
-"checksum mozjs 0.9.5 (registry+https://github.com/rust-lang/crates.io-index)" = "6d1db0edead699324dd1768f74054a5a759de36a8ce92b15e8b179ec2549d19e"
+"checksum mozjs 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)" = "0c7eea7a83e5f237500eb7d66c8ca9c6dc97e3dc4f129eae2dc63fa17fb87f9a"
 "checksum mozjs_sys 0.61.6 (registry+https://github.com/rust-lang/crates.io-index)" = "610d0fce234d68723526bfdc57091f6f4fe5ed661a343125014cd61823711cb5"
 "checksum msdos_time 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "aad9dfe950c057b1bfe9c1f2aa51583a8468ef2a5baba2ebbe06d775efeb7729"
 "checksum muldiv 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "451a9a05d2a32c566c897835e0ea95cf79ed2fdfe957924045a1721a36c9980f"
diff --git a/components/malloc_size_of/Cargo.toml b/components/malloc_size_of/Cargo.toml
index 92b3db44c15..e7acb0de25e 100644
--- a/components/malloc_size_of/Cargo.toml
+++ b/components/malloc_size_of/Cargo.toml
@@ -33,6 +33,7 @@ hashglobe = { path = "../hashglobe" }
 hyper = { version = "0.12", optional = true }
 hyper_serde = { version = "0.9", optional = true }
 keyboard-types = {version = "0.4.3", optional = true}
+mozjs = { version = "0.10.0", optional = true}
 selectors = { path = "../selectors" }
 serde = { version = "1.0.27", optional = true }
 serde_bytes = { version = "0.10", optional = true }
@@ -46,9 +47,3 @@ url = { version = "1.2", optional = true }
 webrender_api = { git = "https://github.com/servo/webrender", features = ["ipc"], optional = true }
 xml5ever = { version = "0.12", optional = true }
 void = "1.0.2"
-
-[target.'cfg(target_os = "android")'.dependencies]
-mozjs = { version = "0.9.5", optional = true, features=["init_once"]}
-
-[target.'cfg(not(target_os = "android"))'.dependencies]
-mozjs = { version = "0.9.5", optional = true}
diff --git a/components/script/Cargo.toml b/components/script/Cargo.toml
index 2e0bd88ea78..e6cb81366d0 100644
--- a/components/script/Cargo.toml
+++ b/components/script/Cargo.toml
@@ -63,6 +63,7 @@ indexmap = "1.0.2"
 ipc-channel = "0.11"
 itertools = "0.8"
 jstraceable_derive = {path = "../jstraceable_derive"}
+js = {package = "mozjs", version = "0.10.0"}
 keyboard-types = "0.4.4"
 lazy_static = "1"
 libc = "0.2"
@@ -114,9 +115,3 @@ webvr_traits = {path = "../webvr_traits"}
 
 [target.'cfg(not(target_os = "ios"))'.dependencies]
 mozangle = "0.1"
-
-[target.'cfg(target_os = "android")'.dependencies]
-js = {package = "mozjs", version = "0.9.5", features=["init_once"]}
-
-[target.'cfg(not(target_os = "android"))'.dependencies]
-js = {package = "mozjs", version = "0.9.5"}
diff --git a/components/script/dom/bindings/codegen/CodegenRust.py b/components/script/dom/bindings/codegen/CodegenRust.py
index e82beb913bc..e7399d66307 100644
--- a/components/script/dom/bindings/codegen/CodegenRust.py
+++ b/components/script/dom/bindings/codegen/CodegenRust.py
@@ -2592,7 +2592,7 @@ class CGConstructorEnabled(CGAbstractMethod):
         return CGList((CGGeneric(cond) for cond in conditions), " &&\n")
 
 
-def CreateBindingJSObject(descriptor, parent=None):
+def CreateBindingJSObject(descriptor):
     assert not descriptor.isGlobal()
     create = "let raw = Box::into_raw(object);\nlet _rt = RootedTraceable::new(&*raw);\n"
     if descriptor.proxy:
@@ -2601,12 +2601,11 @@ let handler = RegisterBindings::PROXY_HANDLERS[PrototypeList::Proxies::%s as usi
 rooted!(in(cx) let private = PrivateValue(raw as *const libc::c_void));
 let obj = NewProxyObject(cx, handler,
                          Handle::from_raw(UndefinedHandleValue),
-                         proto.get(), %s.get(),
-                         ptr::null_mut(), ptr::null_mut());
+                         proto.get());
 assert!(!obj.is_null());
 SetProxyReservedSlot(obj, 0, &private.get());
 rooted!(in(cx) let obj = obj);\
-""" % (descriptor.name, parent)
+""" % (descriptor.name)
     else:
         create += ("rooted!(in(cx) let obj = JS_NewObjectWithGivenProto(\n"
                    "    cx, &Class.base as *const JSClass, proto.handle()));\n"
@@ -2699,7 +2698,7 @@ class CGWrapMethod(CGAbstractMethod):
 
     def definition_body(self):
         unforgeable = CopyUnforgeablePropertiesToInstance(self.descriptor)
-        create = CreateBindingJSObject(self.descriptor, "scope")
+        create = CreateBindingJSObject(self.descriptor)
         return CGGeneric("""\
 let scope = scope.reflector().get_jsobject();
 assert!(!scope.get().is_null());
diff --git a/components/script/dom/dedicatedworkerglobalscope.rs b/components/script/dom/dedicatedworkerglobalscope.rs
index 92e26bad353..00fcd388bf3 100644
--- a/components/script/dom/dedicatedworkerglobalscope.rs
+++ b/components/script/dom/dedicatedworkerglobalscope.rs
@@ -23,7 +23,7 @@ use crate::dom::messageevent::MessageEvent;
 use crate::dom::worker::{TrustedWorkerAddress, Worker};
 use crate::dom::workerglobalscope::WorkerGlobalScope;
 use crate::script_runtime::ScriptThreadEventCategory::WorkerEvent;
-use crate::script_runtime::{new_rt_and_cx, CommonScriptMsg, Runtime, ScriptChan, ScriptPort};
+use crate::script_runtime::{new_child_runtime, CommonScriptMsg, Runtime, ScriptChan, ScriptPort};
 use crate::task_queue::{QueuedTask, QueuedTaskConversion, TaskQueue};
 use crate::task_source::TaskSourceName;
 use crossbeam_channel::{unbounded, Receiver, Sender};
@@ -272,11 +272,9 @@ impl DedicatedWorkerGlobalScope {
         let serialized_worker_url = worker_url.to_string();
         let name = format!("WebWorker for {}", serialized_worker_url);
         let top_level_browsing_context_id = TopLevelBrowsingContextId::installed();
-        let origin = GlobalScope::current()
-            .expect("No current global object")
-            .origin()
-            .immutable()
-            .clone();
+        let current_global = GlobalScope::current().expect("No current global object");
+        let origin = current_global.origin().immutable().clone();
+        let parent = current_global.runtime_handle();
 
         thread::Builder::new()
             .name(name)
@@ -327,7 +325,7 @@ impl DedicatedWorkerGlobalScope {
                 let url = metadata.final_url;
                 let source = String::from_utf8_lossy(&bytes);
 
-                let runtime = unsafe { new_rt_and_cx() };
+                let runtime = unsafe { new_child_runtime(parent) };
 
                 let (devtools_mpsc_chan, devtools_mpsc_port) = unbounded();
                 ROUTER.route_ipc_receiver_to_crossbeam_sender(
diff --git a/components/script/dom/globalscope.rs b/components/script/dom/globalscope.rs
index 4aa3a29cea6..91112299034 100644
--- a/components/script/dom/globalscope.rs
+++ b/components/script/dom/globalscope.rs
@@ -47,7 +47,7 @@ use js::jsapi::{HandleObject, Heap};
 use js::jsapi::{JSAutoCompartment, JSContext};
 use js::panic::maybe_resume_unwind;
 use js::rust::wrappers::Evaluate2;
-use js::rust::{get_object_class, CompileOptionsWrapper, Runtime};
+use js::rust::{get_object_class, CompileOptionsWrapper, ParentRuntime, Runtime};
 use js::rust::{HandleValue, MutableHandleValue};
 use js::{JSCLASS_IS_DOMJSCLASS, JSCLASS_IS_GLOBAL};
 use msg::constellation_msg::PipelineId;
@@ -711,6 +711,16 @@ impl GlobalScope {
         unreachable!();
     }
 
+    pub fn runtime_handle(&self) -> ParentRuntime {
+        if self.is::<Window>() {
+            ScriptThread::runtime_handle()
+        } else if let Some(worker) = self.downcast::<WorkerGlobalScope>() {
+            worker.runtime_handle()
+        } else {
+            unreachable!()
+        }
+    }
+
     /// Returns the ["current"] global object.
     ///
     /// ["current"]: https://html.spec.whatwg.org/multipage/#current
diff --git a/components/script/dom/serviceworkerglobalscope.rs b/components/script/dom/serviceworkerglobalscope.rs
index 23fd1895ea4..116ffffdac5 100644
--- a/components/script/dom/serviceworkerglobalscope.rs
+++ b/components/script/dom/serviceworkerglobalscope.rs
@@ -292,7 +292,7 @@ impl ServiceWorkerGlobalScope {
                         },
                     };
 
-                let runtime = unsafe { new_rt_and_cx() };
+                let runtime = new_rt_and_cx();
 
                 let (devtools_mpsc_chan, devtools_mpsc_port) = unbounded();
                 ROUTER
diff --git a/components/script/dom/workerglobalscope.rs b/components/script/dom/workerglobalscope.rs
index 99cee52eaa1..75987e2aa17 100644
--- a/components/script/dom/workerglobalscope.rs
+++ b/components/script/dom/workerglobalscope.rs
@@ -39,7 +39,7 @@ use ipc_channel::ipc::IpcSender;
 use js::jsapi::{JSAutoCompartment, JSContext};
 use js::jsval::UndefinedValue;
 use js::panic::maybe_resume_unwind;
-use js::rust::HandleValue;
+use js::rust::{HandleValue, ParentRuntime};
 use msg::constellation_msg::PipelineId;
 use net_traits::request::{CredentialsMode, Destination, RequestInit as NetRequestInit};
 use net_traits::{load_whole_resource, IpcSend};
@@ -135,6 +135,10 @@ impl WorkerGlobalScope {
         }
     }
 
+    pub fn runtime_handle(&self) -> ParentRuntime {
+        self.runtime.prepare_for_new_child()
+    }
+
     pub fn from_devtools_sender(&self) -> Option<IpcSender<DevtoolScriptControlMsg>> {
         self.from_devtools_sender.clone()
     }
diff --git a/components/script/dom/worklet.rs b/components/script/dom/worklet.rs
index ac17d99d3aa..16d7ccb5f6b 100644
--- a/components/script/dom/worklet.rs
+++ b/components/script/dom/worklet.rs
@@ -470,7 +470,7 @@ impl WorkletThread {
                 global_init: init.global_init,
                 global_scopes: HashMap::new(),
                 control_buffer: None,
-                runtime: unsafe { new_rt_and_cx() },
+                runtime: new_rt_and_cx(),
                 should_gc: false,
                 gc_threshold: MIN_GC_THRESHOLD,
             });
diff --git a/components/script/script_runtime.rs b/components/script/script_runtime.rs
index d10b95a068e..2ee27ab38bb 100644
--- a/components/script/script_runtime.rs
+++ b/components/script/script_runtime.rs
@@ -42,6 +42,8 @@ use js::panic::wrap_panic;
 use js::rust::wrappers::{GetPromiseIsHandled, GetPromiseResult};
 use js::rust::Handle;
 use js::rust::IntoHandle;
+use js::rust::JSEngine;
+use js::rust::ParentRuntime;
 use js::rust::Runtime as RustRuntime;
 use malloc_size_of::MallocSizeOfOps;
 use msg::constellation_msg::PipelineId;
@@ -56,6 +58,7 @@ use std::os;
 use std::os::raw::c_void;
 use std::panic::AssertUnwindSafe;
 use std::ptr;
+use std::sync::Arc;
 use style::thread_state::{self, ThreadState};
 use time::{now, Tm};
 
@@ -322,10 +325,28 @@ impl Deref for Runtime {
     }
 }
 
+lazy_static! {
+    static ref JS_ENGINE: Arc<JSEngine> = JSEngine::init().unwrap();
+}
+
+#[allow(unsafe_code)]
+pub unsafe fn new_child_runtime(parent: ParentRuntime) -> Runtime {
+    new_rt_and_cx_with_parent(Some(parent))
+}
+
 #[allow(unsafe_code)]
-pub unsafe fn new_rt_and_cx() -> Runtime {
+pub fn new_rt_and_cx() -> Runtime {
+    unsafe { new_rt_and_cx_with_parent(None) }
+}
+
+#[allow(unsafe_code)]
+unsafe fn new_rt_and_cx_with_parent(parent: Option<ParentRuntime>) -> Runtime {
     LiveDOMReferences::initialize();
-    let runtime = RustRuntime::new().unwrap();
+    let runtime = if let Some(parent) = parent {
+        RustRuntime::create_with_parent(parent)
+    } else {
+        RustRuntime::new(JS_ENGINE.clone())
+    };
     let cx = runtime.cx();
 
     JS_AddExtraGCRootsTracer(cx, Some(trace_rust_roots), ptr::null_mut());
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 48dad65a725..4076a56f9ca 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -100,6 +100,7 @@ use js::glue::GetWindowProxyClass;
 use js::jsapi::{JSAutoCompartment, JSContext, JS_SetWrapObjectCallbacks};
 use js::jsapi::{JSTracer, SetWindowProxyClass};
 use js::jsval::UndefinedValue;
+use js::rust::ParentRuntime;
 use metrics::{PaintTimeMetrics, MAX_TASK_NS};
 use mime::{self, Mime};
 use msg::constellation_msg::{
@@ -726,6 +727,13 @@ impl ScriptThreadFactory for ScriptThread {
 }
 
 impl ScriptThread {
+    pub fn runtime_handle() -> ParentRuntime {
+        SCRIPT_THREAD_ROOT.with(|root| {
+            let script_thread = unsafe { &*root.get().unwrap() };
+            script_thread.js_runtime.prepare_for_new_child()
+        })
+    }
+
     pub unsafe fn note_newly_transitioning_nodes(nodes: Vec<UntrustedNodeAddress>) {
         SCRIPT_THREAD_ROOT.with(|root| {
             let script_thread = &*root.get().unwrap();
@@ -1010,7 +1018,7 @@ impl ScriptThread {
         port: Receiver<MainThreadScriptMsg>,
         chan: Sender<MainThreadScriptMsg>,
     ) -> ScriptThread {
-        let runtime = unsafe { new_rt_and_cx() };
+        let runtime = new_rt_and_cx();
         let cx = runtime.cx();
 
         unsafe {