Web Animations CSS: Start running animations on the compositor

Source/core/animation/DocumentTimeline.h

Index: Source/core/animation/DocumentTimeline.h
diff --git a/Source/core/animation/DocumentTimeline.h b/Source/core/animation/DocumentTimeline.h
index d2c64039a0edffb503b8ebf47c9ebad51ea60cad..d15bd01cefb052e454148955daf80bfaede5b140 100644
--- a/Source/core/animation/DocumentTimeline.h
+++ b/Source/core/animation/DocumentTimeline.h
@@ -63,12 +63,15 @@ public:
     // Returns whether style recalc was triggered.
     bool serviceAnimations();
 
+    // Creates a player attached to this timeline, but without a start time.
+    PassRefPtr<Player> createPlayer(TimedItem*);
     PassRefPtr<Player> play(TimedItem*);
 
     // Called from setReadyState() in Document.cpp to set m_zeroTime to
     // performance.timing.domInteractive
     void setZeroTime(double);
     bool hasStarted() const { return !isNull(m_zeroTime); }
+    double zeroTime() const { return m_zeroTime; }
     double currentTime();
     void pauseAnimationsForTesting(double);
     size_t numberOfActiveAnimationsForTesting() const;