Auto merge of #12751 - emilio:transitions-raf, r=pcwalton

compositor: Send animation ticks to layout even if there are script animation frames.

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #12749 (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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The script tick ends up only processing JS callbacks related to animation
frames, so CSS transitions/animations end up not working as expected.

This could have accidentally worked before #12563 because we over-restyled, but
now this is no longer the case.

Other possible way to do it is making a layout reflow with RAF handle CSS
animations/transitions too, but that may not work if the reflow ends up being
suppressed (that could very well be the case), and we'd need to handle a lot
more state in the document, so this solution (assuming it doesn't break try)
seems a bit less flacky.

Missing a test, will add one soon. Fixes #12749.

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3 files changed, 6 insertions, 6 deletions

diff --git a/components/script/dom/testbinding.rs b/components/script/dom/testbinding.rs
index 13579d71330..372055483c7 100644
--- a/components/script/dom/testbinding.rs
+++ b/components/script/dom/testbinding.rs
@@ -613,8 +613,8 @@ impl TestBindingMethods for TestBinding {
         }
     }
 
-    fn AdvanceClock(&self, ms: i32) {
-        self.global().r().as_window().advance_animation_clock(ms);
+    fn AdvanceClock(&self, ms: i32, tick: bool) {
+        self.global().r().as_window().advance_animation_clock(ms, tick);
     }
 
     fn Panic(&self) { panic!("explicit panic from script") }
diff --git a/components/script/dom/webidls/TestBinding.webidl b/components/script/dom/webidls/TestBinding.webidl
index 9fc8a9e3bb6..9945f983ad7 100644
--- a/components/script/dom/webidls/TestBinding.webidl
+++ b/components/script/dom/webidls/TestBinding.webidl
@@ -439,7 +439,7 @@ interface TestBinding {
   [Pref="dom.testbinding.prefcontrolled.enabled"]
   const unsigned short prefControlledConstDisabled = 0;
   [Pref="layout.animations.test.enabled"]
-  void advanceClock(long millis);
+  void advanceClock(long millis, optional boolean forceLayoutTick = true);
 
   [Pref="dom.testbinding.prefcontrolled2.enabled"]
   readonly attribute boolean prefControlledAttributeEnabled;
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index c25c826b4ec..8aaa0adcde3 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -1074,9 +1074,9 @@ impl Window {
     }
 
     /// Advances the layout animation clock by `delta` milliseconds, and then
-    /// forces a reflow.
-    pub fn advance_animation_clock(&self, delta: i32) {
-        self.layout_chan.send(Msg::AdvanceClockMs(delta)).unwrap();
+    /// forces a reflow if `tick` is true.
+    pub fn advance_animation_clock(&self, delta: i32, tick: bool) {
+        self.layout_chan.send(Msg::AdvanceClockMs(delta, tick)).unwrap();
     }
 
     /// Reflows the page unconditionally if possible and not suppressed. This