Auto merge of #17068 - gterzian:remove_compositorproxy, r=asajeffrey

Separate waking the event loop, from communicating with Compositor

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@paulrouget first step of #15934, Glutin only for now, please take a look...

If this makes sense, I will also update the code for ports other than Glutin...

One question: one do I add the `warn!` macro to `servolib`? Also perhaps we would also want to add `box`, since I had to switch to using `Box::new`...

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- [ ] These changes fix #__ (github issue number if applicable).

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components/constellation/constellation.rs

@@ -172,7 +172,7 @@ pub struct Constellation<Message, LTF, STF> {
 
     /// A channel (the implementation of which is port-specific) for the
     /// constellation to send messages to the compositor thread.
-    compositor_proxy: Box<CompositorProxy>,
+    compositor_proxy: CompositorProxy,
 
     /// Channels for the constellation to send messages to the public
     /// resource-related threads.  There are two groups of resource
@@ -302,7 +302,7 @@ pub struct Constellation<Message, LTF, STF> {
 /// State needed to construct a constellation.
 pub struct InitialConstellationState {
     /// A channel through which messages can be sent to the compositor.
-    pub compositor_proxy: Box<CompositorProxy + Send>,
+    pub compositor_proxy: CompositorProxy,
 
     /// A channel to the debugger, if applicable.
     pub debugger_chan: Option<debugger::Sender>,

components/constellation/pipeline.rs

@@ -69,7 +69,7 @@ pub struct Pipeline {
     pub layout_chan: IpcSender<LayoutControlMsg>,
 
     /// A channel to the compositor.
-    pub compositor_proxy: Box<CompositorProxy + 'static + Send>,
+    pub compositor_proxy: CompositorProxy,
 
     /// The most recently loaded URL in this pipeline.
     /// Note that this URL can change, for example if the page navigates
@@ -123,7 +123,7 @@ pub struct InitialPipelineState {
     pub scheduler_chan: IpcSender<TimerSchedulerMsg>,
 
     /// A channel to the compositor.
-    pub compositor_proxy: Box<CompositorProxy + 'static + Send>,
+    pub compositor_proxy: CompositorProxy,
 
     /// A channel to the developer tools, if applicable.
     pub devtools_chan: Option<Sender<DevtoolsControlMsg>>,
@@ -303,7 +303,7 @@ impl Pipeline {
                parent_info: Option<(PipelineId, FrameType)>,
                event_loop: Rc<EventLoop>,
                layout_chan: IpcSender<LayoutControlMsg>,
-               compositor_proxy: Box<CompositorProxy + 'static + Send>,
+               compositor_proxy: CompositorProxy,
                is_private: bool,
                url: ServoUrl,
                visible: bool)