Auto merge of #11364 - Ms2ger:CompositorMsg, r=nox

Move CompositorMsg to script_traits.

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 --faster` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

Either:
- [ ] There are tests for these changes OR
- [x] These changes do not require tests because refactoring

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components/servo/Cargo.lock

@@ -2480,7 +2480,6 @@ dependencies = [
 name = "webdriver_server"
 version = "0.0.1"
 dependencies = [
- "compositing 0.0.1",
  "euclid 0.6.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "hyper 0.9.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "image 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2490,6 +2489,7 @@ dependencies = [
  "plugins 0.0.1",
  "regex 0.1.71 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-serialize 0.3.19 (registry+https://github.com/rust-lang/crates.io-index)",
+ "script_traits 0.0.1",
  "url 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "util 0.0.1",
  "uuid 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",

components/servo/lib.rs

@@ -58,7 +58,6 @@ fn webdriver(port: u16, constellation: Sender<ConstellationMsg>) {
 fn webdriver(_port: u16, _constellation: Sender<ConstellationMsg>) { }
 
 use compositing::CompositorEventListener;
-use compositing::CompositorMsg as ConstellationMsg;
 use compositing::compositor_thread::InitialCompositorState;
 use compositing::windowing::WindowEvent;
 use compositing::windowing::WindowMethods;
@@ -79,6 +78,7 @@ use profile::mem as profile_mem;
 use profile::time as profile_time;
 use profile_traits::mem;
 use profile_traits::time;
+use script_traits::ConstellationMsg;
 use std::rc::Rc;
 use std::sync::mpsc::Sender;
 use util::resource_files::resources_dir_path;