Web Animations: Avoid iteration when checking for outdated animations on timeline

Source/core/animation/Animation.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 166 matching lines @@
         return animation1->sequenceNumber() < animation2->sequenceNumber();
     }
 
     virtual bool addEventListener(const AtomicString& eventType, PassRefPtr<EventListener>, bool useCapture = false) override;
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     Animation(ExecutionContext*, AnimationTimeline&, AnimationEffect*);
 
+    void clearOutdated();
+
     double sourceEnd() const;
     bool limited(double currentTime) const;
 
     AnimationPlayState calculatePlayState();
     double calculateCurrentTime() const;
 
     void unpauseInternal();
     void setPlaybackRateInternal(double);
     void updateCurrentTimingState(TimingUpdateReason);
 
@@ skipping 96 matching lines @@
 
     OwnPtr<WebCompositorAnimationPlayer> m_compositorPlayer;
 
     bool m_currentTimePending;
     bool m_stateIsBeingUpdated;
 };
 
 } // namespace blink
 
 #endif // Animation_h