Auto merge of #8958 - jkachmar:separate-layout-msg, r=KiChjang

Separate script and layout messages, issue #8843

Separated layout-specific messages to the constellation out from the `ScriptMsg` enum into a `LayoutMsg` enum within `script_traits/script_msg.rs`, addresses [#8843](https://github.com/servo/servo/issues/8843).

I initially tried to move `LayoutMsg` into `layout_traits/lib.rs`, but this introduced a cyclic dependency: `layout_traits` depends on `script_traits` for the `LayoutTaskFactory` implementation, and `script_traits/script_task.rs` now depends on `LayoutMsg` for new layout channels in `InitialScriptState` and `ScriptTask`.

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1 files changed, 8 insertions, 1 deletions

diff --git a/components/script/dom/bindings/trace.rs b/components/script/dom/bindings/trace.rs
index cbe870f073c..496d70add18 100644
--- a/components/script/dom/bindings/trace.rs
+++ b/components/script/dom/bindings/trace.rs
@@ -63,7 +63,7 @@ use net_traits::storage_task::StorageType;
 use profile_traits::mem::ProfilerChan as MemProfilerChan;
 use profile_traits::time::ProfilerChan as TimeProfilerChan;
 use script_task::ScriptChan;
-use script_traits::{ScriptMsg, TimerEventId, TimerSource, UntrustedNodeAddress};
+use script_traits::{LayoutMsg, ScriptMsg, TimerEventId, TimerSource, UntrustedNodeAddress};
 use selectors::parser::PseudoElement;
 use selectors::states::*;
 use serde::{Deserialize, Serialize};
@@ -306,6 +306,13 @@ impl JSTraceable for ConstellationChan<ScriptMsg> {
     }
 }
 
+impl JSTraceable for ConstellationChan<LayoutMsg> {
+    #[inline]
+    fn trace(&self, _trc: *mut JSTracer) {
+        // Do nothing
+    }
+}
+
 impl JSTraceable for Box<ScriptChan + Send> {
     #[inline]
     fn trace(&self, _trc: *mut JSTracer) {