style: Use serde to serialize LengthPercentage and StyleRayFunction.

We need to pass these two types into the compositor, so we need a better
way to serialize these rust types. We use serde and bincode to
serialize/deserialize them, and use ByteBuf to pass the &[u8] data
through IPC. We define StyleVecU8 for FFI usage only.

Differential Revision: https://phabricator.services.mozilla.com/D50688

components/style/lib.rs

@@ -78,7 +78,6 @@ extern crate parking_lot;
 extern crate precomputed_hash;
 extern crate rayon;
 extern crate selectors;
-#[cfg(feature = "servo")]
 #[macro_use]
 extern crate serde;
 pub extern crate servo_arc;

components/style/values/computed/angle.rs

@@ -13,16 +13,17 @@ use std::{f32, f64};
 use style_traits::{CssWriter, ToCss};
 
 /// A computed angle in degrees.
-#[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
 #[derive(
     Add,
     Animate,
     Clone,
     Copy,
     Debug,
+    Deserialize,
     MallocSizeOf,
     PartialEq,
     PartialOrd,
+    Serialize,
     ToAnimatedZero,
     ToResolvedValue,
 )]

components/style/values/computed/length.rs

@@ -75,7 +75,9 @@ impl ToComputedValue for specified::Length {
 ///
 /// https://drafts.csswg.org/css-values-4/#typedef-length-percentage
 #[allow(missing_docs)]
-#[derive(Clone, Copy, Debug, MallocSizeOf, ToAnimatedZero, ToResolvedValue)]
+#[derive(
+    Clone, Copy, Debug, Deserialize, MallocSizeOf, Serialize, ToAnimatedZero, ToResolvedValue,
+)]
 #[repr(C)]
 pub struct LengthPercentage {
     length: Length,
@@ -611,9 +613,11 @@ impl Size {
     Clone,
     ComputeSquaredDistance,
     Copy,
+    Deserialize,
     MallocSizeOf,
     PartialEq,
     PartialOrd,
+    Serialize,
     ToAnimatedValue,
     ToAnimatedZero,
     ToResolvedValue,

components/style/values/computed/percentage.rs

@@ -12,7 +12,6 @@ use std::fmt;
 use style_traits::{CssWriter, ToCss};
 
 /// A computed percentage.
-#[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
 #[derive(
     Animate,
     Clone,
@@ -20,9 +19,11 @@ use style_traits::{CssWriter, ToCss};
     Copy,
     Debug,
     Default,
+    Deserialize,
     MallocSizeOf,
     PartialEq,
     PartialOrd,
+    Serialize,
     SpecifiedValueInfo,
     ToAnimatedValue,
     ToAnimatedZero,

components/style/values/generics/motion.rs

@@ -14,9 +14,11 @@ use crate::values::specified::SVGPathData;
     Clone,
     Copy,
     Debug,
+    Deserialize,
     MallocSizeOf,
     Parse,
     PartialEq,
+    Serialize,
     SpecifiedValueInfo,
     ToAnimatedZero,
     ToComputedValue,
@@ -41,8 +43,10 @@ pub enum RaySize {
     Clone,
     ComputeSquaredDistance,
     Debug,
+    Deserialize,
     MallocSizeOf,
     PartialEq,
+    Serialize,
     SpecifiedValueInfo,
     ToAnimatedZero,
     ToComputedValue,