Web Animations: Compositor start notification should only apply to animations in a matching group

Source/core/animation/Animation.h

Index: Source/core/animation/Animation.h
diff --git a/Source/core/animation/Animation.h b/Source/core/animation/Animation.h
index 07b1b3919893f9790d5246fda87010dbefeda70d..9adaffa9565af37bd4962687dc6c753185b9538e 100644
--- a/Source/core/animation/Animation.h
+++ b/Source/core/animation/Animation.h
@@ -76,8 +76,7 @@ public:
 
     bool isCandidateForAnimationOnCompositor(double playerPlaybackRate) const;
     // Must only be called once.
-    bool maybeStartAnimationOnCompositor(double startTime, double timeOffset);
-    bool maybeStartAnimationOnCompositor(double startTime, double timeOffset, double playerPlaybackRate);
+    bool maybeStartAnimationOnCompositor(int group, double startTime, double timeOffset, double playerPlaybackRate);
     bool hasActiveAnimationsOnCompositor() const;
     bool hasActiveAnimationsOnCompositor(CSSPropertyID) const;
     void cancelAnimationOnCompositor();