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

Source/core/animation/TimedItem.cpp

 /*
  * 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 28 matching lines @@
     , m_startTime(0)
     , m_player(0)
     , m_specified(timing)
     , m_eventDelegate(eventDelegate)
     , m_calculated()
     , m_isFirstSample(true)
 {
     timing.assertValid();
 }
 
-void TimedItem::updateInheritedTime(double inheritedTime) const
+bool TimedItem::updateInheritedTime(double inheritedTime) const
 {
     const double localTime = inheritedTime - m_startTime;
     const double iterationDuration = m_specified.hasIterationDuration
         ? m_specified.iterationDuration
         : intrinsicIterationDuration();
 
     const double repeatedDuration = iterationDuration * m_specified.iterationCount;
     const double activeDuration = m_specified.playbackRate
         ? repeatedDuration / abs(m_specified.playbackRate)
         : std::numeric_limits<double>::infinity();
@@ skipping 39 matching lines @@
     m_calculated.isInPlay = phase() == PhaseActive && (!m_parent || m_parent->isInPlay());
     m_calculated.isCurrent = phase() == PhaseBefore || isInPlay() || (m_parent && m_parent->isCurrent());
 
     // This logic is specific to CSS animation events and assumes that all
     // animations start after the DocumentTimeline has started.
     if (m_eventDelegate && (m_isFirstSample || previousPhase != phase() || (phase() == PhaseActive && previousIteration != currentIteration)))
         m_eventDelegate->onEventCondition(this, m_isFirstSample, previousPhase, previousIteration);
     m_isFirstSample = false;
 
     // FIXME: This probably shouldn't be recursive.
-    updateChildrenAndEffects();
+    bool didTriggerStyleRecalc = updateChildrenAndEffects();
 
     m_calculated.timeToEffectChange = calculateTimeToEffectChange(localTime, m_startTime + m_specified.startDelay, m_calculated.phase);
+    return didTriggerStyleRecalc;
 }
 
 } // namespace WebCore