Web Animations: Avoid iteration when checking for outdated animations on timeline

Source/core/animation/AnimationTimeline.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 75 matching lines @@
     double currentTime(bool& isNull);
     double currentTime();
     double currentTimeInternal(bool& isNull);
     double currentTimeInternal();
     void setCurrentTime(double);
     void setCurrentTimeInternal(double);
     double effectiveTime();
     void pauseAnimationsForTesting(double);
 
     void setOutdatedAnimation(Animation*);
-    bool hasOutdatedAnimation() const;
+    void clearOutdatedAnimation(Animation*);
+    bool hasOutdatedAnimation() const { return m_outdatedAnimationCount > 0; }
     bool needsAnimationTimingUpdate();
 
     void setPlaybackRate(double);
     double playbackRate() const;
 
     WebCompositorAnimationTimeline* compositorTimeline() const { return m_compositorTimeline.get(); }
 
     Document* document() { return m_document.get(); }
 #if !ENABLE(OILPAN)
     void detachFromDocument();
 #endif
     void wake();
 
     DECLARE_TRACE();
 
 protected:
     AnimationTimeline(Document*, PassOwnPtrWillBeRawPtr<PlatformTiming>);
 
 private:
     RawPtrWillBeMember<Document> m_document;
     double m_zeroTime;
     bool m_zeroTimeInitialized;
+    unsigned m_outdatedAnimationCount;
     // Animations which will be updated on the next frame
     // i.e. current, in effect, or had timing changed
     WillBeHeapHashSet<RefPtrWillBeMember<Animation>> m_animationsNeedingUpdate;
     WillBeHeapHashSet<RawPtrWillBeWeakMember<Animation>> m_animations;
 
     double m_playbackRate;
 
     friend class SMILTimeContainer;
     static const double s_minimumDelay;
 
@@ skipping 23 matching lines @@
         RawPtrWillBeMember<AnimationTimeline> m_timeline;
         Timer<AnimationTimelineTiming> m_timer;
     };
 
     friend class AnimationAnimationTimelineTest;
 };
 
 } // namespace blink
 
 #endif