Use the new `Unserializable` structure in canvas' `FromPaintMsg`.

components/canvas/canvas_paint_thread.rs

@@ -196,7 +196,7 @@ impl<'a> CanvasPaintThread<'a> {
                         }
                     }
                     CanvasMsg::FromPaint(message) => {
-                        match message {
+                        match message.get() {
                             FromPaintMsg::SendNativeSurface(chan) => {
                                 painter.send_native_surface(chan)
                             }

components/canvas/webgl_paint_thread.rs

@@ -222,7 +222,7 @@ impl WebGLPaintThread {
                         }
                     }
                     CanvasMsg::FromPaint(message) => {
-                        match message {
+                        match message.get() {
                             FromPaintMsg::SendNativeSurface(chan) =>
                                 painter.send_native_surface(chan),
                         }

components/canvas_traits/lib.rs

@@ -35,11 +35,11 @@ use gfx_traits::color;
 use ipc_channel::ipc::{IpcSender, IpcSharedMemory};
 use layers::platform::surface::NativeSurface;
 use offscreen_gl_context::GLContextAttributes;
-use serde::{Deserialize, Deserializer, Serialize, Serializer};
 use std::default::Default;
 use std::fmt;
 use std::str::FromStr;
 use std::sync::mpsc::Sender;
+use util::ipc::Unserializable;
 use util::mem::HeapSizeOf;
 
 #[derive(Clone, Deserialize, Serialize)]
@@ -53,7 +53,7 @@ pub enum CanvasMsg {
     Canvas2d(Canvas2dMsg),
     Common(CanvasCommonMsg),
     FromLayout(FromLayoutMsg),
-    FromPaint(FromPaintMsg),
+    FromPaint(Unserializable<FromPaintMsg>),
     WebGL(CanvasWebGLMsg),
 }
 
@@ -73,18 +73,6 @@ pub enum FromPaintMsg {
     SendNativeSurface(Sender<NativeSurface>),
 }
 
-impl Serialize for FromPaintMsg {
-    fn serialize<S>(&self, _: &mut S) -> Result<(), S::Error> where S: Serializer {
-        panic!("can't serialize a `FromPaintMsg`!")
-    }
-}
-
-impl Deserialize for FromPaintMsg {
-    fn deserialize<D>(_: &mut D) -> Result<FromPaintMsg, D::Error> where D: Deserializer {
-        panic!("can't deserialize a `FromPaintMsg`!")
-    }
-}
-
 #[derive(Clone, Deserialize, Serialize)]
 pub enum Canvas2dMsg {
     Arc(Point2D<f32>, f32, f32, f32, bool),