Auto merge of #11816 - servo:stable-style, r=nox

Make the style crate (almost) build with a stable compiler

<!-- Please describe your changes on the following line: -->

The bulk of this is adding cargo features to make derived implementations of `heapsize` and `serde` traits optional.

"Almost" because `std::intrinsics::discriminant_value` is currently unstable and doesn’t have any stable replacement that I know of. For now, this PR conditionally replaces it with `unimplemented!()`.

r? @nox

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes <s>fix</s> are part of #11815 (github issue number if applicable).

<!-- Either: -->
- [ ] There are tests for these changes OR
- [x] These changes do not <s>require tests</s> *have tests yet* because that requires https://github.com/servo/servo/issues/11806, but I still want to land this before it bitrots. (Tests should check that the build succeeds with a stable compiler.)

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---
This change is [<img src="https://reviewable.io/review_button.svg" height="35" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/11816)
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35 files changed, 361 insertions, 207 deletions

diff --git a/components/style/Cargo.toml b/components/style/Cargo.toml
index 98492645bc7..8a9e207aff2 100644
--- a/components/style/Cargo.toml
+++ b/components/style/Cargo.toml
@@ -12,31 +12,35 @@ path = "lib.rs"
 
 [features]
 gecko = ["gecko_bindings"]
+servo = ["serde", "serde/nightly", "serde_macros", "heapsize", "heapsize_plugin",
+         "style_traits/servo", "app_units/plugins", "euclid/plugins",
+         "cssparser/heap_size", "cssparser/serde-serialization",
+         "selectors/heap_size", "selectors/unstable", "string_cache/heap_size",
+         "url/heap_size"]
 
 [dependencies]
-app_units = {version = "0.2.3", features = ["plugins"]}
+app_units = "0.2.3"
 bitflags = "0.7"
-cssparser = {version = "0.5.5", features = ["heap_size", "serde-serialization"]}
+cssparser = "0.5.5"
 encoding = "0.2"
-euclid = {version = "0.6.4", features = ["plugins"]}
+euclid = "0.6.4"
 fnv = "1.0"
 gecko_bindings = {path = "../../ports/geckolib/gecko_bindings", optional = true}
-heapsize = "0.3.0"
-heapsize_plugin = "0.1.2"
+heapsize = {version = "0.3.0", optional = true}
+heapsize_plugin = {version = "0.1.2", optional = true}
 lazy_static = "0.2"
 log = "0.3.5"
 matches = "0.1"
 num-traits = "0.1.32"
-plugins = {path = "../plugins"}
 rustc-serialize = "0.3"
-selectors = {version = "0.6", features = ["heap_size", "unstable"]}
-serde = {version = "0.7", features = ["nightly"]}
-serde_macros = "0.7"
+selectors = "0.6"
+serde = {version = "0.7", optional = true}
+serde_macros = {version = "0.7", optional = true}
 smallvec = "0.1"
-string_cache = {version = "0.2.20", features = ["heap_size"]}
+string_cache = "0.2.20"
 style_traits = {path = "../style_traits"}
 time = "0.1"
-url = {version = "1.0.0", features = ["heap_size"]}
+url = "1.0.0"
 util = {path = "../util"}
 
 [build-dependencies]
diff --git a/components/style/attr.rs b/components/style/attr.rs
index 42fdbbc853b..e16591f6c37 100644
--- a/components/style/attr.rs
+++ b/components/style/attr.rs
@@ -17,14 +17,16 @@ use values::specified::Length;
 // Duplicated from script::dom::values.
 const UNSIGNED_LONG_MAX: u32 = 2147483647;
 
-#[derive(Clone, Copy, Debug, HeapSizeOf, PartialEq)]
+#[derive(Clone, Copy, Debug, PartialEq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum LengthOrPercentageOrAuto {
     Auto,
     Percentage(f32),
     Length(Au),
 }
 
-#[derive(PartialEq, Clone, HeapSizeOf)]
+#[derive(PartialEq, Clone)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum AttrValue {
     String(String),
     TokenList(String, Vec<Atom>),
@@ -538,7 +540,8 @@ pub fn parse_length(mut value: &str) -> LengthOrPercentageOrAuto {
     }
 }
 
-#[derive(Clone, HeapSizeOf, Debug)]
+#[derive(Clone, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct AttrIdentifier {
     pub local_name: Atom,
     pub name: Atom,
diff --git a/components/style/custom_properties.rs b/components/style/custom_properties.rs
index 80aed5c10c3..957e5899486 100644
--- a/components/style/custom_properties.rs
+++ b/components/style/custom_properties.rs
@@ -23,7 +23,8 @@ pub fn parse_name(s: &str) -> Result<&str, ()> {
     }
 }
 
-#[derive(Clone, PartialEq, Debug, HeapSizeOf)]
+#[derive(Clone, PartialEq, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct SpecifiedValue {
     css: String,
 
@@ -41,7 +42,8 @@ pub struct BorrowedSpecifiedValue<'a> {
     references: Option<&'a HashSet<Name>>,
 }
 
-#[derive(Clone, HeapSizeOf, Debug)]
+#[derive(Clone, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct ComputedValue {
     css: String,
     first_token_type: TokenSerializationType,
diff --git a/components/style/data.rs b/components/style/data.rs
index 3698eeddf5b..ee0975c3737 100644
--- a/components/style/data.rs
+++ b/components/style/data.rs
@@ -33,7 +33,7 @@ impl<Impl, ConcreteComputedValues> PrivateStyleData<Impl, ConcreteComputedValues
 }
 
 /// Information that we need stored in each DOM node.
-#[derive(HeapSizeOf)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct DomParallelInfo {
     /// The number of children that still need work done.
     pub children_count: AtomicIsize,
diff --git a/components/style/dom.rs b/components/style/dom.rs
index 7d10b394989..7713cc1aa0a 100644
--- a/components/style/dom.rs
+++ b/components/style/dom.rs
@@ -31,7 +31,8 @@ pub type UnsafeNode = (usize, usize);
 /// Because the script task's GC does not trace layout, node data cannot be safely stored in layout
 /// data structures. Also, layout code tends to be faster when the DOM is not being accessed, for
 /// locality reasons. Using `OpaqueNode` enforces this invariant.
-#[derive(Clone, PartialEq, Copy, Debug, HeapSizeOf, Hash, Eq, Deserialize, Serialize)]
+#[derive(Clone, PartialEq, Copy, Debug, Hash, Eq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
 pub struct OpaqueNode(pub usize);
 
 impl OpaqueNode {
diff --git a/components/style/element_state.rs b/components/style/element_state.rs
index 9b84bde45c1..e641c450123 100644
--- a/components/style/element_state.rs
+++ b/components/style/element_state.rs
@@ -4,7 +4,7 @@
 
 bitflags! {
     #[doc = "Event-based element states."]
-    #[derive(HeapSizeOf)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub flags ElementState: u16 {
         #[doc = "The mouse is down on this element. \
                  https://html.spec.whatwg.org/multipage/#selector-active \
diff --git a/components/style/error_reporting.rs b/components/style/error_reporting.rs
index d2977d28b3a..1ea1afbd5d1 100644
--- a/components/style/error_reporting.rs
+++ b/components/style/error_reporting.rs
@@ -20,6 +20,6 @@ impl ParseErrorReporter for StdoutErrorReporter {
     }
 
     fn clone(&self) -> Box<ParseErrorReporter + Send + Sync> {
-        box StdoutErrorReporter
+        Box::new(StdoutErrorReporter)
     }
 }
diff --git a/components/style/font_face.rs b/components/style/font_face.rs
index f3876210478..9ecdcffe5d5 100644
--- a/components/style/font_face.rs
+++ b/components/style/font_face.rs
@@ -9,19 +9,22 @@ use properties::longhands::font_family::parse_one_family;
 use std::iter;
 use url::Url;
 
-#[derive(Clone, Debug, HeapSizeOf, PartialEq, Eq, Deserialize, Serialize)]
+#[derive(Clone, Debug, PartialEq, Eq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
 pub enum Source {
     Url(UrlSource),
     Local(FontFamily),
 }
 
-#[derive(Clone, Debug, HeapSizeOf, PartialEq, Eq, Deserialize, Serialize)]
+#[derive(Clone, Debug, PartialEq, Eq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
 pub struct UrlSource {
     pub url: Url,
     pub format_hints: Vec<String>,
 }
 
-#[derive(Debug, HeapSizeOf, PartialEq, Eq)]
+#[derive(Debug, PartialEq, Eq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct FontFaceRule {
     pub family: FontFamily,
     pub sources: Vec<Source>,
@@ -59,7 +62,8 @@ pub fn parse_font_face_block(context: &ParserContext, input: &mut Parser)
     }
 }
 
-#[derive(Clone, Debug, Deserialize, Serialize)]
+#[derive(Clone, Debug)]
+#[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
 pub struct EffectiveSources(Vec<Source>);
 
 impl FontFaceRule {
diff --git a/components/style/lib.rs b/components/style/lib.rs
index 4ec45e45e04..28e2963f4ff 100644
--- a/components/style/lib.rs
+++ b/components/style/lib.rs
@@ -2,17 +2,14 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#![feature(box_syntax)]
-#![feature(box_patterns)]
-#![feature(concat_idents)]
+// FIXME: replace discriminant_value with per-enum methods that use `match`?
 #![feature(core_intrinsics)]
-#![feature(custom_attribute)]
-#![feature(custom_derive)]
-#![feature(plugin)]
 
-#![plugin(heapsize_plugin)]
-#![plugin(plugins)]
-#![plugin(serde_macros)]
+#![cfg_attr(feature = "servo", feature(custom_attribute))]
+#![cfg_attr(feature = "servo", feature(custom_derive))]
+#![cfg_attr(feature = "servo", feature(plugin))]
+#![cfg_attr(feature = "servo", plugin(heapsize_plugin))]
+#![cfg_attr(feature = "servo", plugin(serde_macros))]
 
 #![deny(unsafe_code)]
 
@@ -30,7 +27,7 @@ extern crate euclid;
 extern crate fnv;
 #[cfg(feature = "gecko")]
 extern crate gecko_bindings;
-extern crate heapsize;
+#[cfg(feature = "servo")] extern crate heapsize;
 #[allow(unused_extern_crates)]
 #[macro_use]
 extern crate lazy_static;
@@ -42,7 +39,7 @@ extern crate matches;
 extern crate num_traits;
 extern crate rustc_serialize;
 extern crate selectors;
-extern crate serde;
+#[cfg(feature = "servo")] extern crate serde;
 extern crate smallvec;
 #[macro_use(atom, ns)] extern crate string_cache;
 #[macro_use]
diff --git a/components/style/logical_geometry.rs b/components/style/logical_geometry.rs
index b6afaf6f540..2b41b512910 100644
--- a/components/style/logical_geometry.rs
+++ b/components/style/logical_geometry.rs
@@ -5,7 +5,8 @@
 //! Geometry in flow-relative space.
 
 use euclid::num::Zero;
-use euclid::{Point2D, Rect, SideOffsets2D, Size2D};
+use euclid::side_offsets::SideOffsets2D;
+use euclid::{Point2D, Rect, Size2D};
 use std::cmp::{max, min};
 use std::fmt::{self, Debug, Error, Formatter};
 use std::ops::{Add, Sub};
@@ -22,7 +23,8 @@ pub enum InlineBaseDirection {
 }
 
 bitflags!(
-    #[derive(HeapSizeOf, RustcEncodable)]
+    #[derive(RustcEncodable)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub flags WritingMode: u8 {
         const FLAG_RTL = 1 << 0,
         const FLAG_VERTICAL = 1 << 1,
diff --git a/components/style/media_queries.rs b/components/style/media_queries.rs
index 859b86ea963..87ae0c77722 100644
--- a/components/style/media_queries.rs
+++ b/components/style/media_queries.rs
@@ -10,12 +10,14 @@ use util::geometry::ViewportPx;
 use values::specified;
 
 
-#[derive(Debug, HeapSizeOf, PartialEq)]
+#[derive(Debug, PartialEq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct MediaQueryList {
     pub media_queries: Vec<MediaQuery>
 }
 
-#[derive(PartialEq, Eq, Copy, Clone, Debug, HeapSizeOf)]
+#[derive(PartialEq, Eq, Copy, Clone, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum Range<T> {
     Min(T),
     Max(T),
@@ -58,20 +60,23 @@ impl<T: Ord> Range<T> {
 }
 
 /// http://dev.w3.org/csswg/mediaqueries-3/#media1
-#[derive(PartialEq, Copy, Clone, Debug, HeapSizeOf)]
+#[derive(PartialEq, Copy, Clone, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum Expression {
     /// http://dev.w3.org/csswg/mediaqueries-3/#width
     Width(Range<specified::Length>),
 }
 
 /// http://dev.w3.org/csswg/mediaqueries-3/#media0
-#[derive(PartialEq, Eq, Copy, Clone, Debug, HeapSizeOf)]
+#[derive(PartialEq, Eq, Copy, Clone, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum Qualifier {
     Only,
     Not,
 }
 
-#[derive(Debug, HeapSizeOf, PartialEq)]
+#[derive(Debug, PartialEq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct MediaQuery {
     pub qualifier: Option<Qualifier>,
     pub media_type: MediaQueryType,
@@ -90,20 +95,23 @@ impl MediaQuery {
 }
 
 /// http://dev.w3.org/csswg/mediaqueries-3/#media0
-#[derive(PartialEq, Eq, Copy, Clone, Debug, HeapSizeOf)]
+#[derive(PartialEq, Eq, Copy, Clone, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum MediaQueryType {
     All,  // Always true
     MediaType(MediaType),
 }
 
-#[derive(PartialEq, Eq, Copy, Clone, Debug, HeapSizeOf)]
+#[derive(PartialEq, Eq, Copy, Clone, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum MediaType {
     Screen,
     Print,
     Unknown,
 }
 
-#[derive(Debug, HeapSizeOf)]
+#[derive(Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct Device {
     pub media_type: MediaType,
     pub viewport_size: TypedSize2D<ViewportPx, f32>,
diff --git a/components/style/parallel.rs b/components/style/parallel.rs
index 0700986ee10..e967c3839fd 100644
--- a/components/style/parallel.rs
+++ b/components/style/parallel.rs
@@ -17,7 +17,7 @@ use util::workqueue::{WorkQueue, WorkUnit, WorkerProxy};
 #[allow(dead_code)]
 fn static_assertion(node: UnsafeNode) {
     unsafe {
-        let _: UnsafeNodeList = ::std::intrinsics::transmute(node);
+        let _: UnsafeNodeList = mem::transmute(node);
     }
 }
 
@@ -46,7 +46,7 @@ pub fn traverse_dom<N, C>(root: N,
     run_queue_with_custom_work_data_type(queue, |queue| {
         queue.push(WorkUnit {
             fun:  top_down_dom::<N, C>,
-            data: (box vec![root.to_unsafe()], root.opaque()),
+            data: (Box::new(vec![root.to_unsafe()]), root.opaque()),
         });
     }, queue_data);
 }
@@ -89,7 +89,7 @@ fn top_down_dom<N, C>(unsafe_nodes: UnsafeNodeList,
     for chunk in discovered_child_nodes.chunks(CHUNK_SIZE) {
         proxy.push(WorkUnit {
             fun:  top_down_dom::<N, C>,
-            data: (box chunk.iter().cloned().collect(), unsafe_nodes.1),
+            data: (Box::new(chunk.iter().cloned().collect()), unsafe_nodes.1),
         });
     }
 }
diff --git a/components/style/properties/longhand/background.mako.rs b/components/style/properties/longhand/background.mako.rs
index 77be57aa097..aaac791c0e8 100644
--- a/components/style/properties/longhand/background.mako.rs
+++ b/components/style/properties/longhand/background.mako.rs
@@ -17,7 +17,8 @@ ${helpers.predefined_type(
 
     pub mod computed_value {
         use values::computed;
-        #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+        #[derive(Debug, Clone, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Option<computed::Image>);
     }
 
@@ -32,7 +33,8 @@ ${helpers.predefined_type(
         }
     }
 
-    #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+    #[derive(Debug, Clone, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue(pub Option<Image>);
 
     impl ToCss for SpecifiedValue {
@@ -77,14 +79,16 @@ ${helpers.predefined_type(
         pub mod computed_value {
             use values::computed::LengthOrPercentage;
 
-            #[derive(PartialEq, Copy, Clone, Debug, HeapSizeOf)]
+            #[derive(PartialEq, Copy, Clone, Debug)]
+            #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
             pub struct T {
                 pub horizontal: LengthOrPercentage,
                 pub vertical: LengthOrPercentage,
             }
         }
 
-        #[derive(Debug, Clone, PartialEq, Copy, HeapSizeOf)]
+        #[derive(Debug, Clone, PartialEq, Copy)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct SpecifiedValue {
             pub horizontal: specified::LengthOrPercentage,
             pub vertical: specified::LengthOrPercentage,
@@ -198,13 +202,15 @@ ${helpers.single_keyword("background-origin", "padding-box border-box content-bo
     pub mod computed_value {
         use values::computed::LengthOrPercentageOrAuto;
 
-        #[derive(PartialEq, Clone, Debug, HeapSizeOf)]
+        #[derive(PartialEq, Clone, Debug)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct ExplicitSize {
             pub width: LengthOrPercentageOrAuto,
             pub height: LengthOrPercentageOrAuto,
         }
 
-        #[derive(PartialEq, Clone, Debug, HeapSizeOf)]
+        #[derive(PartialEq, Clone, Debug)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub enum T {
             Explicit(ExplicitSize),
             Cover,
@@ -222,7 +228,8 @@ ${helpers.single_keyword("background-origin", "padding-box border-box content-bo
         }
     }
 
-    #[derive(Clone, PartialEq, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedExplicitSize {
         pub width: specified::LengthOrPercentageOrAuto,
         pub height: specified::LengthOrPercentageOrAuto,
@@ -245,7 +252,8 @@ ${helpers.single_keyword("background-origin", "padding-box border-box content-bo
     }
 
 
-    #[derive(Clone, PartialEq, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         Explicit(SpecifiedExplicitSize),
         Cover,
diff --git a/components/style/properties/longhand/border.mako.rs b/components/style/properties/longhand/border.mako.rs
index fac233a6924..96656861583 100644
--- a/components/style/properties/longhand/border.mako.rs
+++ b/components/style/properties/longhand/border.mako.rs
@@ -34,7 +34,8 @@
                                -> Result<SpecifiedValue, ()> {
             specified::parse_border_width(input).map(SpecifiedValue)
         }
-        #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+        #[derive(Debug, Clone, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct SpecifiedValue(pub specified::Length);
         pub mod computed_value {
             use app_units::Au;
diff --git a/components/style/properties/longhand/box.mako.rs b/components/style/properties/longhand/box.mako.rs
index 800cf276a1a..eddc2da5053 100644
--- a/components/style/properties/longhand/box.mako.rs
+++ b/components/style/properties/longhand/box.mako.rs
@@ -28,8 +28,8 @@
 
     pub mod computed_value {
         #[allow(non_camel_case_types)]
-        #[derive(Clone, Eq, PartialEq, Copy, Hash, RustcEncodable, Debug, HeapSizeOf)]
-        #[derive(Deserialize, Serialize)]
+        #[derive(Clone, Eq, PartialEq, Copy, Hash, RustcEncodable, Debug)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
         pub enum T {
             % for value in values:
                 ${to_rust_ident(value)},
@@ -136,7 +136,8 @@ ${helpers.single_keyword("clear", "none left right both", gecko_ffi_name="mBreak
   <% vertical_align_keywords = vertical_align.keyword.values_for(product) %>
 
   #[allow(non_camel_case_types)]
-  #[derive(Debug, Clone, PartialEq, Copy, HeapSizeOf)]
+  #[derive(Debug, Clone, PartialEq, Copy)]
+  #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
   pub enum SpecifiedValue {
       % for keyword in vertical_align_keywords:
           ${to_rust_ident(keyword)},
@@ -174,7 +175,8 @@ ${helpers.single_keyword("clear", "none left right both", gecko_ffi_name="mBreak
       use values::AuExtensionMethods;
       use values::{CSSFloat, computed};
       #[allow(non_camel_case_types)]
-      #[derive(PartialEq, Copy, Clone, HeapSizeOf, Debug)]
+      #[derive(PartialEq, Copy, Clone, Debug)]
+      #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
       pub enum T {
           % for keyword in vertical_align_keywords:
               ${to_rust_ident(keyword)},
@@ -243,7 +245,8 @@ ${helpers.single_keyword("overflow-x", "visible hidden scroll auto", need_clone=
   }
 
   pub mod computed_value {
-      #[derive(Debug, Clone, Copy, PartialEq, HeapSizeOf)]
+      #[derive(Debug, Clone, Copy, PartialEq)]
+      #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
       pub struct T(pub super::super::overflow_x::computed_value::T);
   }
 
@@ -279,7 +282,8 @@ ${helpers.single_keyword("overflow-x", "visible hidden scroll auto", need_clone=
 
         pub use values::computed::Time as SingleComputedValue;
 
-        #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+        #[derive(Debug, Clone, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Vec<SingleComputedValue>);
 
         impl ToComputedValue for T {
@@ -385,7 +389,8 @@ ${helpers.single_keyword("overflow-x", "visible hidden scroll auto", need_clone=
 
         pub use self::TransitionTimingFunction as SingleComputedValue;
 
-        #[derive(Copy, Clone, Debug, PartialEq, HeapSizeOf)]
+        #[derive(Copy, Clone, Debug, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub enum TransitionTimingFunction {
             CubicBezier(Point2D<f32>, Point2D<f32>),
             Steps(u32, StartEnd),
@@ -416,7 +421,8 @@ ${helpers.single_keyword("overflow-x", "visible hidden scroll auto", need_clone=
             }
         }
 
-        #[derive(Copy, Clone, Debug, PartialEq, HeapSizeOf)]
+        #[derive(Copy, Clone, Debug, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub enum StartEnd {
             Start,
             End,
@@ -431,7 +437,8 @@ ${helpers.single_keyword("overflow-x", "visible hidden scroll auto", need_clone=
             }
         }
 
-        #[derive(Clone, Debug, PartialEq, HeapSizeOf)]
+        #[derive(Clone, Debug, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Vec<TransitionTimingFunction>);
 
         impl ToCss for T {
@@ -537,7 +544,8 @@ ${helpers.single_keyword("overflow-x", "visible hidden scroll auto", need_clone=
 
         pub use self::TransitionProperty as SingleComputedValue;
 
-        #[derive(Copy, Clone, Debug, PartialEq, HeapSizeOf)]
+        #[derive(Copy, Clone, Debug, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub enum TransitionProperty {
             All,
             BackgroundColor,
@@ -688,7 +696,8 @@ ${helpers.single_keyword("overflow-x", "visible hidden scroll auto", need_clone=
             }
         }
 
-        #[derive(Clone, Debug, PartialEq, HeapSizeOf)]
+        #[derive(Clone, Debug, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Vec<SingleComputedValue>);
 
         impl ToCss for T {
@@ -863,14 +872,16 @@ ${helpers.single_keyword("-moz-appearance",
     use url::Url;
     use values::computed::ComputedValueAsSpecified;
 
-    #[derive(PartialEq, Clone, Debug, HeapSizeOf)]
+    #[derive(PartialEq, Clone, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct UrlExtraData {
         pub base: GeckoArcURI,
         pub referrer: GeckoArcURI,
         pub principal: GeckoArcPrincipal,
     }
 
-    #[derive(PartialEq, Clone, Debug, HeapSizeOf)]
+    #[derive(PartialEq, Clone, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         Url(Url, UrlExtraData),
         None,
diff --git a/components/style/properties/longhand/column.mako.rs b/components/style/properties/longhand/column.mako.rs
index b040b9bd41e..cf24613496e 100644
--- a/components/style/properties/longhand/column.mako.rs
+++ b/components/style/properties/longhand/column.mako.rs
@@ -11,7 +11,8 @@
     use std::fmt;
     use values::AuExtensionMethods;
 
-    #[derive(Debug, Clone, Copy, PartialEq, HeapSizeOf)]
+    #[derive(Debug, Clone, Copy, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         Auto,
         Specified(specified::Length),
@@ -28,7 +29,8 @@
 
     pub mod computed_value {
         use app_units::Au;
-        #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+        #[derive(Debug, Clone, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Option<Au>);
     }
 
@@ -72,7 +74,8 @@
     use cssparser::ToCss;
     use std::fmt;
 
-    #[derive(Debug, Clone, Copy, PartialEq, HeapSizeOf)]
+    #[derive(Debug, Clone, Copy, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         Auto,
         Specified(u32),
@@ -88,7 +91,8 @@
     }
 
     pub mod computed_value {
-        #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+        #[derive(Debug, Clone, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Option<u32>);
     }
 
@@ -138,7 +142,8 @@
     use std::fmt;
     use values::AuExtensionMethods;
 
-    #[derive(Debug, Clone, Copy, PartialEq, HeapSizeOf)]
+    #[derive(Debug, Clone, Copy, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         Normal,
         Specified(specified::Length),
@@ -155,7 +160,8 @@
 
     pub mod computed_value {
         use app_units::Au;
-        #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+        #[derive(Debug, Clone, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Option<Au>);
     }
 
diff --git a/components/style/properties/longhand/counters.mako.rs b/components/style/properties/longhand/counters.mako.rs
index 1f881b8e9ce..6dd97da6032 100644
--- a/components/style/properties/longhand/counters.mako.rs
+++ b/components/style/properties/longhand/counters.mako.rs
@@ -24,7 +24,8 @@
         use cssparser::{self, ToCss};
         use std::fmt;
 
-        #[derive(Debug, PartialEq, Eq, Clone, HeapSizeOf)]
+        #[derive(Debug, PartialEq, Eq, Clone)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub enum ContentItem {
             /// Literal string content.
             String(String),
@@ -73,7 +74,8 @@
         }
 
         #[allow(non_camel_case_types)]
-        #[derive(Debug, PartialEq, Eq, Clone, HeapSizeOf)]
+        #[derive(Debug, PartialEq, Eq, Clone)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub enum T {
             normal,
             none,
@@ -180,7 +182,8 @@
     pub use self::computed_value::T as SpecifiedValue;
 
     pub mod computed_value {
-        #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+        #[derive(Debug, Clone, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Vec<(String,i32)>);
     }
 
diff --git a/components/style/properties/longhand/effects.mako.rs b/components/style/properties/longhand/effects.mako.rs
index 96f832bb782..005d3576acd 100644
--- a/components/style/properties/longhand/effects.mako.rs
+++ b/components/style/properties/longhand/effects.mako.rs
@@ -16,10 +16,12 @@ ${helpers.predefined_type("opacity",
     use std::fmt;
     use values::AuExtensionMethods;
 
-    #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+    #[derive(Debug, Clone, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue(Vec<SpecifiedBoxShadow>);
 
-    #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+    #[derive(Debug, Clone, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedBoxShadow {
         pub offset_x: specified::Length,
         pub offset_y: specified::Length,
@@ -72,10 +74,12 @@ ${helpers.predefined_type("opacity",
         use std::fmt;
         use values::computed;
 
-        #[derive(Clone, PartialEq, HeapSizeOf, Debug)]
+        #[derive(Clone, PartialEq, Debug)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Vec<BoxShadow>);
 
-        #[derive(Clone, PartialEq, Copy, HeapSizeOf, Debug)]
+        #[derive(Clone, PartialEq, Copy, Debug)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct BoxShadow {
             pub offset_x: Au,
             pub offset_y: Au,
@@ -229,7 +233,8 @@ ${helpers.predefined_type("opacity",
     pub mod computed_value {
         use app_units::Au;
 
-        #[derive(Clone, PartialEq, Eq, Copy, Debug, HeapSizeOf)]
+        #[derive(Clone, PartialEq, Eq, Copy, Debug)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct ClipRect {
             pub top: Au,
             pub right: Option<Au>,
@@ -237,7 +242,8 @@ ${helpers.predefined_type("opacity",
             pub left: Au,
         }
 
-        #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+        #[derive(Debug, Clone, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Option<ClipRect>);
     }
 
@@ -271,7 +277,8 @@ ${helpers.predefined_type("opacity",
         }
     }
 
-    #[derive(Clone, Debug, PartialEq, Copy, HeapSizeOf)]
+    #[derive(Clone, Debug, PartialEq, Copy)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedClipRect {
         pub top: specified::Length,
         pub right: Option<specified::Length>,
@@ -279,7 +286,8 @@ ${helpers.predefined_type("opacity",
         pub left: specified::Length,
     }
 
-    #[derive(Clone, Debug, PartialEq, Copy, HeapSizeOf)]
+    #[derive(Clone, Debug, PartialEq, Copy)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue(Option<SpecifiedClipRect>);
 
     impl ToCss for SpecifiedClipRect {
@@ -394,11 +402,13 @@ ${helpers.predefined_type("opacity",
     use values::CSSFloat;
     use values::specified::{Angle, Length};
 
-    #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+    #[derive(Debug, Clone, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue(Vec<SpecifiedFilter>);
 
     // TODO(pcwalton): `drop-shadow`
-    #[derive(Clone, PartialEq, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedFilter {
         Blur(Length),
         Brightness(CSSFloat),
@@ -416,7 +426,8 @@ ${helpers.predefined_type("opacity",
         use values::CSSFloat;
         use values::specified::{Angle};
 
-        #[derive(Clone, PartialEq, Debug, HeapSizeOf, Deserialize, Serialize)]
+        #[derive(Clone, PartialEq, Debug)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
         pub enum Filter {
             Blur(Au),
             Brightness(CSSFloat),
@@ -429,7 +440,8 @@ ${helpers.predefined_type("opacity",
             Sepia(CSSFloat),
         }
 
-        #[derive(Clone, PartialEq, Debug, HeapSizeOf, Deserialize, Serialize)]
+        #[derive(Clone, PartialEq, Debug)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
         pub struct T { pub filters: Vec<Filter> }
 
         impl T {
@@ -629,7 +641,8 @@ ${helpers.predefined_type("opacity",
         use values::CSSFloat;
         use values::computed;
 
-        #[derive(Clone, Copy, Debug, PartialEq, HeapSizeOf)]
+        #[derive(Clone, Copy, Debug, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct ComputedMatrix {
             pub m11: CSSFloat, pub m12: CSSFloat, pub m13: CSSFloat, pub m14: CSSFloat,
             pub m21: CSSFloat, pub m22: CSSFloat, pub m23: CSSFloat, pub m24: CSSFloat,
@@ -648,7 +661,8 @@ ${helpers.predefined_type("opacity",
             }
         }
 
-        #[derive(Clone, Debug, PartialEq, HeapSizeOf)]
+        #[derive(Clone, Debug, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub enum ComputedOperation {
             Matrix(ComputedMatrix),
             Skew(computed::Angle, computed::Angle),
@@ -660,7 +674,8 @@ ${helpers.predefined_type("opacity",
             Perspective(computed::Length),
         }
 
-        #[derive(Clone, Debug, PartialEq, HeapSizeOf)]
+        #[derive(Clone, Debug, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Option<Vec<ComputedOperation>>);
     }
 
@@ -695,7 +710,8 @@ ${helpers.predefined_type("opacity",
         Ok((first, second))
     }
 
-    #[derive(Copy, Clone, Debug, PartialEq, HeapSizeOf)]
+    #[derive(Copy, Clone, Debug, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     enum TranslateKind {
         Translate,
         TranslateX,
@@ -704,7 +720,8 @@ ${helpers.predefined_type("opacity",
         Translate3D,
     }
 
-    #[derive(Clone, Debug, PartialEq, HeapSizeOf)]
+    #[derive(Clone, Debug, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     enum SpecifiedOperation {
         Matrix(SpecifiedMatrix),
         Skew(specified::Angle, specified::Angle),
@@ -783,7 +800,8 @@ ${helpers.predefined_type("opacity",
         }
     }
 
-    #[derive(Clone, Debug, PartialEq, HeapSizeOf)]
+    #[derive(Clone, Debug, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue(Vec<SpecifiedOperation>);
 
     impl ToCss for SpecifiedValue {
@@ -1173,7 +1191,8 @@ ${helpers.single_keyword("transform-style", "auto flat preserve-3d")}
     pub mod computed_value {
         use values::computed::{Length, LengthOrPercentage};
 
-        #[derive(Clone, Copy, Debug, PartialEq, HeapSizeOf)]
+        #[derive(Clone, Copy, Debug, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T {
             pub horizontal: LengthOrPercentage,
             pub vertical: LengthOrPercentage,
@@ -1181,7 +1200,8 @@ ${helpers.single_keyword("transform-style", "auto flat preserve-3d")}
         }
     }
 
-    #[derive(Clone, Copy, Debug, PartialEq, HeapSizeOf)]
+    #[derive(Clone, Copy, Debug, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue {
         horizontal: LengthOrPercentage,
         vertical: LengthOrPercentage,
@@ -1253,7 +1273,8 @@ ${helpers.predefined_type("perspective",
     pub mod computed_value {
         use values::computed::LengthOrPercentage;
 
-        #[derive(Clone, Copy, Debug, PartialEq, HeapSizeOf)]
+        #[derive(Clone, Copy, Debug, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T {
             pub horizontal: LengthOrPercentage,
             pub vertical: LengthOrPercentage,
@@ -1268,7 +1289,8 @@ ${helpers.predefined_type("perspective",
         }
     }
 
-    #[derive(Clone, Copy, Debug, PartialEq, HeapSizeOf)]
+    #[derive(Clone, Copy, Debug, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue {
         horizontal: LengthOrPercentage,
         vertical: LengthOrPercentage,
diff --git a/components/style/properties/longhand/font.mako.rs b/components/style/properties/longhand/font.mako.rs
index aeef47c94fb..cf63c578adb 100644
--- a/components/style/properties/longhand/font.mako.rs
+++ b/components/style/properties/longhand/font.mako.rs
@@ -19,7 +19,8 @@
         use std::fmt;
         use string_cache::Atom;
 
-        #[derive(Debug, PartialEq, Eq, Clone, Hash, HeapSizeOf, Deserialize, Serialize)]
+        #[derive(Debug, PartialEq, Eq, Clone, Hash)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
         pub enum FontFamily {
             FamilyName(Atom),
             Generic(Atom),
@@ -73,7 +74,8 @@
                 Ok(())
             }
         }
-        #[derive(Debug, Clone, PartialEq, Eq, Hash, HeapSizeOf)]
+        #[derive(Debug, Clone, PartialEq, Eq, Hash)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Vec<FontFamily>);
     }
 
@@ -122,7 +124,8 @@ ${helpers.single_keyword("font-variant", "normal small-caps")}
     use cssparser::ToCss;
     use std::fmt;
 
-    #[derive(Debug, Clone, PartialEq, Eq, Copy, HeapSizeOf)]
+    #[derive(Debug, Clone, PartialEq, Eq, Copy)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         Bolder,
         Lighter,
@@ -169,7 +172,8 @@ ${helpers.single_keyword("font-variant", "normal small-caps")}
     }
     pub mod computed_value {
         use std::fmt;
-        #[derive(PartialEq, Eq, Copy, Clone, Hash, Deserialize, Serialize, HeapSizeOf, Debug)]
+        #[derive(PartialEq, Eq, Copy, Clone, Hash, Debug)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
         #[repr(u16)]
         pub enum T {
             % for weight in range(100, 901, 100):
@@ -250,7 +254,8 @@ ${helpers.single_keyword("font-variant", "normal small-caps")}
         }
     }
 
-    #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+    #[derive(Debug, Clone, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue(pub specified::LengthOrPercentage);
     pub mod computed_value {
         use app_units::Au;
diff --git a/components/style/properties/longhand/inherited_box.mako.rs b/components/style/properties/longhand/inherited_box.mako.rs
index 655d9dac674..482780f3a6e 100644
--- a/components/style/properties/longhand/inherited_box.mako.rs
+++ b/components/style/properties/longhand/inherited_box.mako.rs
@@ -40,7 +40,8 @@ ${helpers.single_keyword("color-adjust", "economy exact", products="gecko")}
         use cssparser::ToCss;
         use std::fmt;
 
-        #[derive(Copy, Clone, Debug, PartialEq, HeapSizeOf, Deserialize, Serialize)]
+        #[derive(Copy, Clone, Debug, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
         pub enum T {
             Auto,
             CrispEdges,
@@ -96,7 +97,8 @@ ${helpers.single_keyword("color-adjust", "economy exact", products="gecko")}
     use std::fmt;
     use values::computed::ComputedValueAsSpecified;
 
-    #[derive(Copy, Clone, Debug, Eq, PartialEq, HeapSizeOf, Serialize, Deserialize)]
+    #[derive(Copy, Clone, Debug, Eq, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
     pub struct SpecifiedValue(pub bool);
 
     pub mod computed_value {
diff --git a/components/style/properties/longhand/inherited_table.mako.rs b/components/style/properties/longhand/inherited_table.mako.rs
index 2a45b2fd43a..8837412cd9a 100644
--- a/components/style/properties/longhand/inherited_table.mako.rs
+++ b/components/style/properties/longhand/inherited_table.mako.rs
@@ -20,14 +20,16 @@ ${helpers.single_keyword("caption-side", "top bottom", extra_gecko_values="right
     pub mod computed_value {
         use app_units::Au;
 
-        #[derive(Clone, Copy, Debug, PartialEq, RustcEncodable, HeapSizeOf)]
+        #[derive(Clone, Copy, Debug, PartialEq, RustcEncodable)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T {
             pub horizontal: Au,
             pub vertical: Au,
         }
     }
 
-    #[derive(Clone, Debug, PartialEq, HeapSizeOf)]
+    #[derive(Clone, Debug, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue {
         pub horizontal: specified::Length,
         pub vertical: specified::Length,
diff --git a/components/style/properties/longhand/inherited_text.mako.rs b/components/style/properties/longhand/inherited_text.mako.rs
index dedc6e60102..358d260459a 100644
--- a/components/style/properties/longhand/inherited_text.mako.rs
+++ b/components/style/properties/longhand/inherited_text.mako.rs
@@ -12,7 +12,8 @@
     use values::AuExtensionMethods;
     use values::CSSFloat;
 
-    #[derive(Debug, Clone, PartialEq, Copy, HeapSizeOf)]
+    #[derive(Debug, Clone, PartialEq, Copy)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         Normal,
         % if product == "gecko":
@@ -61,7 +62,8 @@
         use app_units::Au;
         use std::fmt;
         use values::CSSFloat;
-        #[derive(PartialEq, Copy, Clone, HeapSizeOf, Debug)]
+        #[derive(PartialEq, Copy, Clone, Debug)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub enum T {
             Normal,
             % if product == "gecko":
@@ -182,7 +184,8 @@
     use std::fmt;
     use values::AuExtensionMethods;
 
-    #[derive(Debug, Clone, Copy, PartialEq, HeapSizeOf)]
+    #[derive(Debug, Clone, Copy, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         Normal,
         Specified(specified::Length),
@@ -199,7 +202,8 @@
 
     pub mod computed_value {
         use app_units::Au;
-        #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+        #[derive(Debug, Clone, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Option<Au>);
     }
 
@@ -244,7 +248,8 @@
     use std::fmt;
     use values::AuExtensionMethods;
 
-    #[derive(Debug, Clone, Copy, PartialEq, HeapSizeOf)]
+    #[derive(Debug, Clone, Copy, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         Normal,
         Specified(specified::Length),  // FIXME(SimonSapin) support percentages
@@ -261,7 +266,8 @@
 
     pub mod computed_value {
         use app_units::Au;
-        #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+        #[derive(Debug, Clone, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Option<Au>);
     }
 
@@ -332,7 +338,8 @@ ${helpers.single_keyword("text-justify",
 
     impl ComputedValueAsSpecified for SpecifiedValue {}
 
-    #[derive(Clone, PartialEq, Copy, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Copy, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue {
         pub underline: Option<RGBA>,
         pub overline: Option<RGBA>,
@@ -446,10 +453,12 @@ ${helpers.single_keyword("text-justify",
     use std::fmt;
     use values::AuExtensionMethods;
 
-    #[derive(Clone, PartialEq, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue(Vec<SpecifiedTextShadow>);
 
-    #[derive(Clone, PartialEq, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedTextShadow {
         pub offset_x: specified::Length,
         pub offset_y: specified::Length,
@@ -461,10 +470,12 @@ ${helpers.single_keyword("text-justify",
         use app_units::Au;
         use cssparser::Color;
 
-        #[derive(Clone, PartialEq, Debug, HeapSizeOf)]
+        #[derive(Clone, PartialEq, Debug)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Vec<TextShadow>);
 
-        #[derive(Clone, PartialEq, Debug, HeapSizeOf)]
+        #[derive(Clone, PartialEq, Debug)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct TextShadow {
             pub offset_x: Au,
             pub offset_y: Au,
diff --git a/components/style/properties/longhand/list.mako.rs b/components/style/properties/longhand/list.mako.rs
index 309e248c2dd..298f387cf13 100644
--- a/components/style/properties/longhand/list.mako.rs
+++ b/components/style/properties/longhand/list.mako.rs
@@ -31,7 +31,8 @@ ${helpers.single_keyword("list-style-type", """
     use url::Url;
     use values::LocalToCss;
 
-    #[derive(Debug, Clone, PartialEq, Eq, HeapSizeOf)]
+    #[derive(Debug, Clone, PartialEq, Eq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum SpecifiedValue {
         None,
         Url(Url),
@@ -52,7 +53,8 @@ ${helpers.single_keyword("list-style-type", """
         use url::Url;
         use values::LocalToCss;
 
-        #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+        #[derive(Debug, Clone, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Option<Url>);
 
         impl ToCss for T {
@@ -100,7 +102,8 @@ ${helpers.single_keyword("list-style-type", """
     pub use self::computed_value::T as SpecifiedValue;
 
     pub mod computed_value {
-        #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+        #[derive(Debug, Clone, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct T(pub Vec<(String,String)>);
     }
 
diff --git a/components/style/properties/longhand/outline.mako.rs b/components/style/properties/longhand/outline.mako.rs
index afa2c9a06c7..ee91fc06499 100644
--- a/components/style/properties/longhand/outline.mako.rs
+++ b/components/style/properties/longhand/outline.mako.rs
@@ -41,7 +41,8 @@ ${helpers.predefined_type("outline-color", "CSSColor", "::cssparser::Color::Curr
     pub fn parse(_context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue, ()> {
         specified::parse_border_width(input).map(SpecifiedValue)
     }
-    #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+    #[derive(Debug, Clone, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue(pub specified::Length);
     pub mod computed_value {
         use app_units::Au;
diff --git a/components/style/properties/longhand/pointing.mako.rs b/components/style/properties/longhand/pointing.mako.rs
index 7068a951b0e..c2ad1502a9e 100644
--- a/components/style/properties/longhand/pointing.mako.rs
+++ b/components/style/properties/longhand/pointing.mako.rs
@@ -17,7 +17,8 @@
         use std::fmt;
         use style_traits::cursor::Cursor;
 
-        #[derive(Clone, PartialEq, Eq, Copy, Debug, HeapSizeOf)]
+        #[derive(Clone, PartialEq, Eq, Copy, Debug)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub enum T {
             AutoCursor,
             SpecifiedCursor(Cursor),
diff --git a/components/style/properties/longhand/position.mako.rs b/components/style/properties/longhand/position.mako.rs
index bc93a6614e5..5ce0b83f87d 100644
--- a/components/style/properties/longhand/position.mako.rs
+++ b/components/style/properties/longhand/position.mako.rs
@@ -20,7 +20,8 @@
         use cssparser::ToCss;
         use std::fmt;
 
-        #[derive(PartialEq, Clone, Eq, Copy, Debug, HeapSizeOf)]
+        #[derive(PartialEq, Clone, Eq, Copy, Debug)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub enum T {
             Auto,
             Number(i32),
diff --git a/components/style/properties/longhand/text.mako.rs b/components/style/properties/longhand/text.mako.rs
index 9bf491a4546..2e34a0c6243 100644
--- a/components/style/properties/longhand/text.mako.rs
+++ b/components/style/properties/longhand/text.mako.rs
@@ -24,7 +24,8 @@ ${helpers.single_keyword("unicode-bidi", "normal embed isolate bidi-override iso
 
     impl ComputedValueAsSpecified for SpecifiedValue {}
 
-    #[derive(PartialEq, Eq, Copy, Clone, Debug, HeapSizeOf)]
+    #[derive(PartialEq, Eq, Copy, Clone, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct SpecifiedValue {
         pub underline: bool,
         pub overline: bool,
diff --git a/components/style/properties/properties.mako.rs b/components/style/properties/properties.mako.rs
index 3d41c30366b..6d57a635748 100644
--- a/components/style/properties/properties.mako.rs
+++ b/components/style/properties/properties.mako.rs
@@ -25,7 +25,7 @@ use cssparser::{Parser, RGBA, AtRuleParser, DeclarationParser, Delimiter,
                 DeclarationListParser, parse_important, ToCss, TokenSerializationType};
 use error_reporting::ParseErrorReporter;
 use url::Url;
-use euclid::SideOffsets2D;
+use euclid::side_offsets::SideOffsets2D;
 use euclid::size::Size2D;
 use string_cache::Atom;
 use computed_values;
@@ -261,11 +261,12 @@ use std::slice;
 /// Overridden declarations are skipped.
 
 // FIXME (https://github.com/servo/servo/issues/3426)
-#[derive(Debug, PartialEq, HeapSizeOf)]
+#[derive(Debug, PartialEq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct PropertyDeclarationBlock {
-    #[ignore_heap_size_of = "#7038"]
+    #[cfg_attr(feature = "servo", ignore_heap_size_of = "#7038")]
     pub important: Arc<Vec<PropertyDeclaration>>,
-    #[ignore_heap_size_of = "#7038"]
+    #[cfg_attr(feature = "servo", ignore_heap_size_of = "#7038")]
     pub normal: Arc<Vec<PropertyDeclaration>>,
 }
 
@@ -616,7 +617,8 @@ impl CSSWideKeyword {
     }
 }
 
-#[derive(Clone, Copy, Eq, PartialEq, Debug, HeapSizeOf)]
+#[derive(Clone, Copy, Eq, PartialEq, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum Shorthand {
     % for property in data.shorthands:
         ${property.camel_case},
@@ -722,7 +724,8 @@ impl Shorthand {
     }
 }
 
-#[derive(Clone, PartialEq, Eq, Debug, HeapSizeOf)]
+#[derive(Clone, PartialEq, Eq, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum DeclaredValue<T> {
     Value(T),
     WithVariables {
@@ -753,7 +756,8 @@ impl<T: ToCss> ToCss for DeclaredValue<T> {
     }
 }
 
-#[derive(PartialEq, Clone, Debug, HeapSizeOf)]
+#[derive(PartialEq, Clone, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum PropertyDeclaration {
     % for property in data.longhands:
         ${property.camel_case}(DeclaredValue<longhands::${property.ident}::SpecifiedValue>),
@@ -1064,9 +1068,11 @@ pub mod style_structs {
 
     % for style_struct in data.active_style_structs():
         % if style_struct.trait_name == "Font":
-        #[derive(Clone, HeapSizeOf, Debug)]
+        #[derive(Clone, Debug)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         % else:
-        #[derive(PartialEq, Clone, HeapSizeOf)]
+        #[derive(PartialEq, Clone)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         % endif
         pub struct ${style_struct.servo_struct_name} {
             % for longhand in style_struct.longhands:
@@ -1233,7 +1239,8 @@ pub trait ComputedValues : Clone + Send + Sync + 'static {
     fn is_multicol(&self) -> bool;
 }
 
-#[derive(Clone, HeapSizeOf)]
+#[derive(Clone)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct ServoComputedValues {
     % for style_struct in data.active_style_structs():
         ${style_struct.ident}: Arc<style_structs::${style_struct.servo_struct_name}>,
@@ -1692,7 +1699,7 @@ pub fn make_cascade_vec<C: ComputedValues>() -> Vec<Option<CascadePropertyFn<C>>
         % for property in style_struct.longhands:
             let discriminant;
             unsafe {
-                let variant = PropertyDeclaration::${property.camel_case}(intrinsics::uninit());
+                let variant = PropertyDeclaration::${property.camel_case}(mem::uninitialized());
                 discriminant = intrinsics::discriminant_value(&variant) as usize;
                 mem::forget(variant);
             }
diff --git a/components/style/restyle_hints.rs b/components/style/restyle_hints.rs
index 3a90852c13a..361d7110d04 100644
--- a/components/style/restyle_hints.rs
+++ b/components/style/restyle_hints.rs
@@ -50,7 +50,8 @@ bitflags! {
 /// now to reduce complexity, but it's worth measuring the performance impact (if any) of the
 /// mStateMask approach.
 
-#[derive(HeapSizeOf, Clone)]
+#[derive(Clone)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct ElementSnapshot {
     pub state: Option<ElementState>,
     pub attrs: Option<Vec<(AttrIdentifier, AttrValue)>>,
@@ -225,7 +226,8 @@ fn combinator_to_restyle_hint(combinator: Option<Combinator>) -> RestyleHint {
     }
 }
 
-#[derive(Debug, HeapSizeOf)]
+#[derive(Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 struct Sensitivities {
     pub states: ElementState,
     pub attrs: bool,
@@ -262,14 +264,16 @@ impl Sensitivities {
 // us to quickly scan through the dependency sites of all style rules and determine the
 // maximum effect that a given state or attribute change may have on the style of
 // elements in the document.
-#[derive(Debug, HeapSizeOf)]
+#[derive(Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 struct Dependency<Impl: SelectorImplExt> {
     selector: Arc<CompoundSelector<Impl>>,
     combinator: Option<Combinator>,
     sensitivities: Sensitivities,
 }
 
-#[derive(Debug, HeapSizeOf)]
+#[derive(Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct DependencySet<Impl: SelectorImplExt> {
     deps: Vec<Dependency<Impl>>,
 }
diff --git a/components/style/selector_impl.rs b/components/style/selector_impl.rs
index 14e6b366690..6125415df78 100644
--- a/components/style/selector_impl.rs
+++ b/components/style/selector_impl.rs
@@ -95,7 +95,8 @@ pub trait SelectorImplExt : SelectorImpl + Sized {
     fn get_quirks_mode_stylesheet() -> Option<&'static Stylesheet<Self>>;
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, HeapSizeOf, Hash)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum PseudoElement {
     Before,
     After,
@@ -117,7 +118,8 @@ impl PseudoElement {
     }
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, HeapSizeOf, Hash)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum NonTSPseudoClass {
     AnyLink,
     Link,
@@ -158,7 +160,8 @@ impl NonTSPseudoClass {
     }
 }
 
-#[derive(Clone, Debug, PartialEq, HeapSizeOf)]
+#[derive(Clone, Debug, PartialEq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct ServoSelectorImpl;
 
 impl SelectorImpl for ServoSelectorImpl {
diff --git a/components/style/selector_matching.rs b/components/style/selector_matching.rs
index 79f590f5482..50bbf7dab49 100644
--- a/components/style/selector_matching.rs
+++ b/components/style/selector_matching.rs
@@ -44,7 +44,7 @@ lazy_static! {
                         None,
                         None,
                         Origin::UserAgent,
-                        box StdoutErrorReporter,
+                        Box::new(StdoutErrorReporter),
                         ParserContextExtraData::default());
                     stylesheets.push(ua_stylesheet);
                 }
@@ -56,7 +56,7 @@ lazy_static! {
         }
         for &(ref contents, ref url) in &opts::get().user_stylesheets {
             stylesheets.push(Stylesheet::from_bytes(
-                &contents, url.clone(), None, None, Origin::User, box StdoutErrorReporter,
+                &contents, url.clone(), None, None, Origin::User, Box::new(StdoutErrorReporter),
                 ParserContextExtraData::default()));
         }
         stylesheets
@@ -73,7 +73,7 @@ lazy_static! {
                     None,
                     None,
                     Origin::UserAgent,
-                    box StdoutErrorReporter,
+                    Box::new(StdoutErrorReporter),
                     ParserContextExtraData::default())
             },
             Err(..) => {
@@ -100,7 +100,7 @@ lazy_static! {
 /// `ServoSelectorImpl`, the implementation used by Servo's layout system in
 /// regular builds, or `GeckoSelectorImpl`, the implementation used in the
 /// geckolib port.
-#[derive(HeapSizeOf)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct Stylist<Impl: SelectorImplExt> {
     /// Device that the stylist is currently evaluating against.
     pub device: Device,
@@ -269,7 +269,7 @@ impl<Impl: SelectorImplExt> Stylist<Impl> {
                 properties::cascade(self.device.au_viewport_size(),
                                     &declarations, false,
                                     parent.map(|p| &**p), None,
-                                    box StdoutErrorReporter);
+                                    Box::new(StdoutErrorReporter));
             Some(Arc::new(computed))
         } else {
             parent.map(|p| p.clone())
@@ -302,7 +302,7 @@ impl<Impl: SelectorImplExt> Stylist<Impl> {
             properties::cascade(self.device.au_viewport_size(),
                                 &declarations, false,
                                 Some(&**parent), None,
-                                box StdoutErrorReporter);
+                                Box::new(StdoutErrorReporter));
         Some(Arc::new(computed))
     }
 
@@ -438,7 +438,7 @@ impl<Impl: SelectorImplExt> Stylist<Impl> {
 }
 
 /// Map that contains the CSS rules for a given origin.
-#[derive(HeapSizeOf)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 struct PerOriginSelectorMap<Impl: SelectorImpl> {
     /// Rules that contains at least one property declararion with
     /// normal importance.
@@ -460,7 +460,7 @@ impl<Impl: SelectorImpl> PerOriginSelectorMap<Impl> {
 
 /// Map that contains the CSS rules for a specific PseudoElement
 /// (or lack of PseudoElement).
-#[derive(HeapSizeOf)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 struct PerPseudoElementSelectorMap<Impl: SelectorImpl> {
     /// Rules from user agent stylesheets
     user_agent: PerOriginSelectorMap<Impl>,
diff --git a/components/style/stylesheets.rs b/components/style/stylesheets.rs
index 4de57e81d40..53990e7f84f 100644
--- a/components/style/stylesheets.rs
+++ b/components/style/stylesheets.rs
@@ -24,7 +24,8 @@ use viewport::ViewportRule;
 /// Each style rule has an origin, which determines where it enters the cascade.
 ///
 /// http://dev.w3.org/csswg/css-cascade/#cascading-origins
-#[derive(Clone, PartialEq, Eq, Copy, Debug, HeapSizeOf)]
+#[derive(Clone, PartialEq, Eq, Copy, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum Origin {
     /// http://dev.w3.org/csswg/css-cascade/#cascade-origin-ua
     UserAgent,
@@ -37,7 +38,8 @@ pub enum Origin {
 }
 
 
-#[derive(Debug, HeapSizeOf, PartialEq)]
+#[derive(Debug, PartialEq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct Stylesheet<Impl: SelectorImpl> {
     /// List of rules in the order they were found (important for
     /// cascading order)
@@ -49,7 +51,8 @@ pub struct Stylesheet<Impl: SelectorImpl> {
 }
 
 
-#[derive(Debug, HeapSizeOf, PartialEq)]
+#[derive(Debug, PartialEq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum CSSRule<Impl: SelectorImpl> {
     Charset(String),
     Namespace(Option<String>, Namespace),
@@ -59,7 +62,8 @@ pub enum CSSRule<Impl: SelectorImpl> {
     Viewport(ViewportRule),
 }
 
-#[derive(Debug, HeapSizeOf, PartialEq)]
+#[derive(Debug, PartialEq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct MediaRule<Impl: SelectorImpl> {
     pub media_queries: MediaQueryList,
     pub rules: Vec<CSSRule<Impl>>,
@@ -72,7 +76,8 @@ impl<Impl: SelectorImpl> MediaRule<Impl> {
     }
 }
 
-#[derive(Debug, HeapSizeOf, PartialEq)]
+#[derive(Debug, PartialEq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct StyleRule<Impl: SelectorImpl> {
     pub selectors: Vec<Selector<Impl>>,
     pub declarations: PropertyDeclarationBlock,
diff --git a/components/style/traversal.rs b/components/style/traversal.rs
index 1afdcbb34c7..d383cc5f706 100644
--- a/components/style/traversal.rs
+++ b/components/style/traversal.rs
@@ -53,11 +53,11 @@ fn take_thread_local_bloom_filter<N, Impl: SelectorImplExt>(parent_node: Option<
             // Root node. Needs new bloom filter.
             (None,     _  ) => {
                 debug!("[{}] No parent, but new bloom filter!", tid());
-                box BloomFilter::new()
+                Box::new(BloomFilter::new())
             }
             // No bloom filter for this thread yet.
             (Some(parent), None) => {
-                let mut bloom_filter = box BloomFilter::new();
+                let mut bloom_filter = Box::new(BloomFilter::new());
                 insert_ancestors_into_bloom_filter(&mut bloom_filter, parent, root);
                 bloom_filter
             }
diff --git a/components/style/values.rs b/components/style/values.rs
index a6c73977d44..6d62d69357e 100644
--- a/components/style/values.rs
+++ b/components/style/values.rs
@@ -41,8 +41,8 @@ macro_rules! define_numbered_css_keyword_enum {
     };
     ($name: ident: $( $css: expr => $variant: ident = $value: expr ),+) => {
         #[allow(non_camel_case_types)]
-        #[derive(Clone, Eq, PartialEq, PartialOrd, Ord, Copy, RustcEncodable, Debug, HeapSizeOf)]
-        #[derive(Deserialize, Serialize)]
+        #[derive(Clone, Eq, PartialEq, PartialOrd, Ord, Copy, RustcEncodable, Debug)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
         pub enum $name {
             $( $variant = $value ),+
         }
@@ -104,7 +104,8 @@ pub mod specified {
     use super::{CSSFloat, FONT_MEDIUM_PX};
     use url::Url;
 
-    #[derive(Clone, PartialEq, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct CSSColor {
         pub parsed: cssparser::Color,
         pub authored: Option<String>,
@@ -133,7 +134,8 @@ pub mod specified {
         }
     }
 
-    #[derive(Clone, PartialEq, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct CSSRGBA {
         pub parsed: cssparser::RGBA,
         pub authored: Option<String>,
@@ -148,7 +150,8 @@ pub mod specified {
         }
     }
 
-    #[derive(Clone, PartialEq, Copy, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Copy, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum FontRelativeLength {
         Em(CSSFloat),
         Ex(CSSFloat),
@@ -185,7 +188,8 @@ pub mod specified {
         }
     }
 
-    #[derive(Clone, PartialEq, Copy, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Copy, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum ViewportPercentageLength {
         Vw(CSSFloat),
         Vh(CSSFloat),
@@ -226,7 +230,8 @@ pub mod specified {
         }
     }
 
-    #[derive(Clone, PartialEq, Copy, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Copy, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct CharacterWidth(pub i32);
 
     impl CharacterWidth {
@@ -241,7 +246,8 @@ pub mod specified {
         }
     }
 
-    #[derive(Clone, PartialEq, Copy, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Copy, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum Length {
         Absolute(Au),  // application units
         FontRelative(FontRelativeLength),
@@ -439,9 +445,9 @@ pub mod specified {
                 SimplifiedValueNode::Angle(Angle(a)) => SimplifiedValueNode::Angle(Angle(a * scalar)),
                 SimplifiedValueNode::Time(Time(t)) => SimplifiedValueNode::Time(Time(t * scalar)),
                 SimplifiedValueNode::Number(n) => SimplifiedValueNode::Number(n * scalar),
-                SimplifiedValueNode::Sum(box ref s) => {
-                    let sum = s * scalar;
-                    SimplifiedValueNode::Sum(box sum)
+                SimplifiedValueNode::Sum(ref s) => {
+                    let sum = &**s * scalar;
+                    SimplifiedValueNode::Sum(Box::new(sum))
                 }
             }
         }
@@ -507,7 +513,8 @@ pub mod specified {
         Time,
     }
 
-    #[derive(Clone, PartialEq, Copy, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Copy, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct CalcLengthOrPercentage {
         pub absolute: Option<Au>,
         pub vw: Option<ViewportPercentageLength>,
@@ -589,7 +596,7 @@ pub mod specified {
                     Ok(CalcValueNode::Percentage(value.unit_value)),
                 (Token::ParenthesisBlock, _) => {
                     input.parse_nested_block(|i| CalcLengthOrPercentage::parse_sum(i, expected_unit))
-                         .map(|result| CalcValueNode::Sum(box result))
+                         .map(|result| CalcValueNode::Sum(Box::new(result)))
                 },
                 _ => Err(())
             }
@@ -598,7 +605,7 @@ pub mod specified {
         fn simplify_value_to_number(node: &CalcValueNode) -> Option<CSSFloat> {
             match *node {
                 CalcValueNode::Number(number) => Some(number),
-                CalcValueNode::Sum(box ref sum) => CalcLengthOrPercentage::simplify_sum_to_number(sum),
+                CalcValueNode::Sum(ref sum) => CalcLengthOrPercentage::simplify_sum_to_number(sum),
                 _ => None
             }
         }
@@ -629,7 +636,7 @@ pub mod specified {
             let mut simplified = Vec::new();
             for product in &node.products {
                 match try!(CalcLengthOrPercentage::simplify_product(product)) {
-                    SimplifiedValueNode::Sum(box sum) => simplified.extend_from_slice(&sum.values),
+                    SimplifiedValueNode::Sum(ref sum) => simplified.extend_from_slice(&sum.values),
                     val => simplified.push(val),
                 }
             }
@@ -637,7 +644,7 @@ pub mod specified {
             if simplified.len() == 1 {
                 Ok(simplified[0].clone())
             } else {
-                Ok(SimplifiedValueNode::Sum(box SimplifiedSumNode { values: simplified } ))
+                Ok(SimplifiedValueNode::Sum(Box::new(SimplifiedSumNode { values: simplified })))
             }
         }
 
@@ -649,7 +656,7 @@ pub mod specified {
                     Some(number) => multiplier *= number,
                     _ if node_with_unit.is_none() => {
                         node_with_unit = Some(match *node {
-                            CalcValueNode::Sum(box ref sum) =>
+                            CalcValueNode::Sum(ref sum) =>
                                 try!(CalcLengthOrPercentage::simplify_products_in_sum(sum)),
                             CalcValueNode::Length(l) => SimplifiedValueNode::Length(l),
                             CalcValueNode::Angle(a) => SimplifiedValueNode::Angle(a),
@@ -855,7 +862,8 @@ pub mod specified {
          }
     }
 
-    #[derive(Clone, PartialEq, Copy, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Copy, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct Percentage(pub CSSFloat); // [0 .. 100%] maps to [0.0 .. 1.0]
 
     impl ToCss for Percentage {
@@ -864,7 +872,8 @@ pub mod specified {
         }
     }
 
-    #[derive(Clone, PartialEq, Copy, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Copy, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum LengthOrPercentage {
         Length(Length),
         Percentage(Percentage),
@@ -912,7 +921,8 @@ pub mod specified {
         }
     }
 
-    #[derive(Clone, PartialEq, Copy, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Copy, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum LengthOrPercentageOrAuto {
         Length(Length),
         Percentage(Percentage),
@@ -961,7 +971,8 @@ pub mod specified {
         }
     }
 
-    #[derive(Clone, PartialEq, Copy, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Copy, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum LengthOrPercentageOrNone {
         Length(Length),
         Percentage(Percentage),
@@ -1009,7 +1020,8 @@ pub mod specified {
         }
     }
 
-    #[derive(Clone, PartialEq, Copy, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Copy, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum LengthOrNone {
         Length(Length),
         None,
@@ -1049,7 +1061,8 @@ pub mod specified {
         }
     }
 
-    #[derive(Clone, PartialEq, Copy, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Copy, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum LengthOrPercentageOrAutoOrContent {
         Length(Length),
         Percentage(Percentage),
@@ -1093,7 +1106,8 @@ pub mod specified {
         }
     }
 
-    #[derive(Clone, PartialEq, Copy, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Copy, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct BorderRadiusSize(pub Size2D<LengthOrPercentage>);
 
     impl BorderRadiusSize {
@@ -1169,7 +1183,8 @@ pub mod specified {
         }
     }
 
-    #[derive(Clone, PartialEq, PartialOrd, Copy, Debug, HeapSizeOf, Deserialize, Serialize)]
+    #[derive(Clone, PartialEq, PartialOrd, Copy, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
     pub struct Angle(pub CSSFloat);
 
     impl ToCss for Angle {
@@ -1215,7 +1230,8 @@ pub mod specified {
     }
 
     /// Specified values for an image according to CSS-IMAGES.
-    #[derive(Clone, PartialEq, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum Image {
         Url(Url),
         LinearGradient(LinearGradient),
@@ -1250,7 +1266,8 @@ pub mod specified {
     }
 
     /// Specified values for a CSS linear gradient.
-    #[derive(Clone, PartialEq, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct LinearGradient {
         /// The angle or corner of the gradient.
         pub angle_or_corner: AngleOrCorner,
@@ -1273,7 +1290,8 @@ pub mod specified {
     }
 
     /// Specified values for an angle or a corner in a linear gradient.
-    #[derive(Clone, PartialEq, Copy, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Copy, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum AngleOrCorner {
         Angle(Angle),
         Corner(HorizontalDirection, VerticalDirection),
@@ -1295,7 +1313,8 @@ pub mod specified {
     }
 
     /// Specified values for one color stop in a linear gradient.
-    #[derive(Clone, PartialEq, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct ColorStop {
         /// The color of this stop.
         pub color: CSSColor,
@@ -1424,7 +1443,8 @@ pub mod specified {
     }
 
     /// A time in seconds according to CSS-VALUES § 6.2.
-    #[derive(Clone, Copy, Debug, PartialEq, PartialOrd, HeapSizeOf)]
+    #[derive(Clone, Copy, Debug, PartialEq, PartialOrd)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct Time(pub CSSFloat);
 
     impl Time {
@@ -1473,7 +1493,8 @@ pub mod specified {
         }
     }
 
-    #[derive(Clone, Copy, Debug, PartialEq, PartialOrd, HeapSizeOf)]
+    #[derive(Clone, Copy, Debug, PartialEq, PartialOrd)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct Number(pub CSSFloat);
 
     impl Number {
@@ -1510,7 +1531,8 @@ pub mod specified {
         }
     }
 
-    #[derive(Clone, Copy, Debug, PartialEq, PartialOrd, HeapSizeOf)]
+    #[derive(Clone, Copy, Debug, PartialEq, PartialOrd)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct Opacity(pub CSSFloat);
 
     impl Opacity {
@@ -1630,7 +1652,8 @@ pub mod computed {
         }
     }
 
-    #[derive(Clone, PartialEq, Copy, Debug, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Copy, Debug)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct CalcLengthOrPercentage {
         pub length: Option<Au>,
         pub percentage: Option<CSSFloat>,
@@ -1734,7 +1757,8 @@ pub mod computed {
     }
 
 
-    #[derive(PartialEq, Clone, Copy, HeapSizeOf)]
+    #[derive(PartialEq, Clone, Copy)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct BorderRadiusSize(pub Size2D<LengthOrPercentage>);
 
     impl BorderRadiusSize {
@@ -1762,7 +1786,8 @@ pub mod computed {
         }
     }
 
-    #[derive(PartialEq, Clone, Copy, HeapSizeOf)]
+    #[derive(PartialEq, Clone, Copy)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum LengthOrPercentage {
         Length(Au),
         Percentage(CSSFloat),
@@ -1827,7 +1852,8 @@ pub mod computed {
         }
     }
 
-    #[derive(PartialEq, Clone, Copy, HeapSizeOf)]
+    #[derive(PartialEq, Clone, Copy)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum LengthOrPercentageOrAuto {
         Length(Au),
         Percentage(CSSFloat),
@@ -1894,7 +1920,8 @@ pub mod computed {
         }
     }
 
-    #[derive(PartialEq, Clone, Copy, HeapSizeOf)]
+    #[derive(PartialEq, Clone, Copy)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum LengthOrPercentageOrAutoOrContent {
         Length(Au),
         Percentage(CSSFloat),
@@ -1952,7 +1979,8 @@ pub mod computed {
         }
     }
 
-    #[derive(PartialEq, Clone, Copy, HeapSizeOf)]
+    #[derive(PartialEq, Clone, Copy)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum LengthOrPercentageOrNone {
         Length(Au),
         Percentage(CSSFloat),
@@ -2004,7 +2032,8 @@ pub mod computed {
         }
     }
 
-    #[derive(PartialEq, Clone, Copy, HeapSizeOf)]
+    #[derive(PartialEq, Clone, Copy)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum LengthOrNone {
         Length(Au),
         None,
@@ -2062,7 +2091,8 @@ pub mod computed {
 
 
     /// Computed values for an image according to CSS-IMAGES.
-    #[derive(Clone, PartialEq, HeapSizeOf)]
+    #[derive(Clone, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub enum Image {
         Url(Url),
         LinearGradient(LinearGradient),
@@ -2078,7 +2108,8 @@ pub mod computed {
     }
 
     /// Computed values for a CSS linear gradient.
-    #[derive(Clone, PartialEq, HeapSizeOf)]
+    #[derive(Clone, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct LinearGradient {
         /// The angle or corner of the gradient.
         pub angle_or_corner: AngleOrCorner,
@@ -2111,7 +2142,8 @@ pub mod computed {
     }
 
     /// Computed values for one color stop in a linear gradient.
-    #[derive(Clone, PartialEq, Copy, HeapSizeOf)]
+    #[derive(Clone, PartialEq, Copy)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
     pub struct ColorStop {
         /// The color of this stop.
         pub color: CSSColor,
diff --git a/components/style/viewport.rs b/components/style/viewport.rs
index e9308f5403a..ec7e1f8aa4a 100644
--- a/components/style/viewport.rs
+++ b/components/style/viewport.rs
@@ -21,7 +21,8 @@ use util::geometry::ViewportPx;
 use values::computed::{Context, ToComputedValue};
 use values::specified::{Length, LengthOrPercentageOrAuto, ViewportPercentageLength};
 
-#[derive(Copy, Clone, Debug, HeapSizeOf, PartialEq)]
+#[derive(Copy, Clone, Debug, PartialEq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum ViewportDescriptor {
     MinWidth(ViewportLength),
     MaxWidth(ViewportLength),
@@ -45,7 +46,8 @@ trait FromMeta: Sized {
 // See:
 // * http://dev.w3.org/csswg/css-device-adapt/#min-max-width-desc
 // * http://dev.w3.org/csswg/css-device-adapt/#extend-to-zoom
-#[derive(Copy, Clone, Debug, HeapSizeOf, PartialEq)]
+#[derive(Copy, Clone, Debug, PartialEq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum ViewportLength {
     Specified(LengthOrPercentageOrAuto),
     ExtendToZoom
@@ -133,7 +135,8 @@ struct ViewportRuleParser<'a, 'b: 'a> {
     context: &'a ParserContext<'b>
 }
 
-#[derive(Copy, Clone, Debug, HeapSizeOf, PartialEq)]
+#[derive(Copy, Clone, Debug, PartialEq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct ViewportDescriptorDeclaration {
     pub origin: Origin,
     pub descriptor: ViewportDescriptor,
@@ -228,7 +231,8 @@ impl<'a, 'b> DeclarationParser for ViewportRuleParser<'a, 'b> {
     }
 }
 
-#[derive(Debug, HeapSizeOf, PartialEq)]
+#[derive(Debug, PartialEq)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct ViewportRule {
     pub declarations: Vec<ViewportDescriptorDeclaration>
 }