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

Source/core/animation/CompositorAnimations.h

Index: Source/core/animation/CompositorAnimations.h
diff --git a/Source/core/animation/CompositorAnimations.h b/Source/core/animation/CompositorAnimations.h
index b076aa5885c98b5f9acc787a22e5f7b92178199f..0f6add9e19807f9dfd4d1f7d00afd0d07671099a 100644
--- a/Source/core/animation/CompositorAnimations.h
+++ b/Source/core/animation/CompositorAnimations.h
@@ -49,7 +49,7 @@ public:
     virtual bool isCandidateForAnimationOnCompositor(const Timing&, const AnimationEffect&, double playerPlaybackRate);
     virtual bool canStartAnimationOnCompositor(const Element&);
     // FIXME: This should return void. We should know ahead of time whether these animations can be started.
-    virtual bool startAnimationOnCompositor(const Element&, double startTime, double timeOffset, const Timing&, const AnimationEffect&, Vector<int>& startedAnimationIds, double playerPlaybackRate);
+    virtual bool startAnimationOnCompositor(const Element&, int group, double startTime, double timeOffset, const Timing&, const AnimationEffect&, Vector<int>& startedAnimationIds, double playerPlaybackRate);
     virtual void cancelAnimationOnCompositor(const Element&, int id);
     virtual void pauseAnimationForTestingOnCompositor(const Element&, int id, double pauseTime);