Defer starting of animations until after compositing update

Source/core/animation/AnimationClock.h

Index: Source/core/animation/AnimationClock.h
diff --git a/Source/core/animation/AnimationClock.h b/Source/core/animation/AnimationClock.h
index f6a2cdb84991f6777818a1f67bf251d269e1b757..540dfbeb2ebd126188b648a079d5a337dfb46ee1 100644
--- a/Source/core/animation/AnimationClock.h
+++ b/Source/core/animation/AnimationClock.h
@@ -36,6 +36,13 @@
 
 namespace WebCore {
 
+// FIXME: This value is used to suppress updates when time is required outside of a frame.
+// The purpose of allowing the clock to update during such periods is to allow animations
+// to have an appropriate start time and for getComputedStyle to attempt to catch-up to a
+// compositor animation. However a more accurate system might be to attempt to phase-lock
+// with the frame clock.
+const double minTimeBeforeUnsynchronizedAnimationClockTick = 0.005;
+
 class AnimationClock {
 public:
     static PassOwnPtr<AnimationClock> create(WTF::TimeFunction monotonicallyIncreasingTime = WTF::monotonicallyIncreasingTime)
@@ -43,22 +50,9 @@ public:
         return adoptPtr(new AnimationClock(monotonicallyIncreasingTime));
     }
 
-    void updateTime(double time)
-    {
-        if (time > m_time)
-            m_time = time;
-        m_frozen = true;
-    }
-
-    double currentTime()
-    {
-        if (!m_frozen)
-            updateTime(m_monotonicallyIncreasingTime());
-        return m_time;
-    }
-
+    void updateTime(double time);
+    double currentTime();
     void unfreeze() { m_frozen = false; }
-
     void resetTimeForTesting() { m_time = 0; m_frozen = true; }
 
 private: