Web Animations CSS: Unfreeze AnimationClock if sampling timelines does not trigger style recalc

Source/core/animation/DocumentTimeline.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 42 matching lines @@
     public:
         // Calls DocumentTimeline's wake() method after duration seconds.
         virtual void wakeAfter(double duration) = 0;
         virtual void cancelWake() = 0;
         virtual void serviceOnNextFrame() = 0;
         virtual ~PlatformTiming() { }
 
     };
 
     static PassRefPtr<DocumentTimeline> create(Document*, PassOwnPtr<PlatformTiming> = nullptr);
-    void serviceAnimations(double);
+    // Returns whether style recalc was triggered.
+    bool serviceAnimations();
     PassRefPtr<Player> play(TimedItem*);
     // Called from setReadyState() in Document.cpp to set m_zeroTime to
     // performance.timing.domInteractive
     void setZeroTime(double);
     double currentTime();
     void pauseAnimationsForTesting(double);
     size_t numberOfActiveAnimationsForTesting() const;
 
     void addEventToDispatch(EventTarget* target, PassRefPtr<Event> event)
     {
@@ skipping 47 matching lines @@
         Timer<DocumentTimelineTiming> m_timer;
 
     };
 
     friend class CoreAnimationDocumentTimelineTest;
 };
 
 } // namespace
 
 #endif