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

Source/core/animation/Animation.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 44 matching lines @@
 {
     if (m_activeInAnimationStack)
         clearEffects();
 }
 
 static AnimationStack& ensureAnimationStack(Element* element)
 {
     return element->ensureActiveAnimations()->defaultStack();
 }
 
-void Animation::applyEffects(bool previouslyInEffect)
+bool Animation::applyEffects(bool previouslyInEffect)
 {
     ASSERT(player());
     if (!m_target || !m_effect)
-        return;
+        return false;
 
     if (!previouslyInEffect) {
         ensureAnimationStack(m_target.get()).add(this);
         m_activeInAnimationStack = true;
     }
 
     m_compositableValues = m_effect->sample(currentIteration(), timeFraction());
     m_target->setNeedsStyleRecalc(LocalStyleChange, StyleChangeFromRenderer);
+    return true;
 }
 
 void Animation::clearEffects()
 {
     ASSERT(player());
     ASSERT(m_activeInAnimationStack);
     ensureAnimationStack(m_target.get()).remove(this);
     m_activeInAnimationStack = false;
     m_compositableValues.clear();
     m_target->setNeedsStyleRecalc(LocalStyleChange, StyleChangeFromRenderer);
 }
 
-void Animation::updateChildrenAndEffects() const
+bool Animation::updateChildrenAndEffects() const
 {
     if (!m_effect)
-        return;
+        return false;
 
     if (isInEffect())
-        const_cast<Animation*>(this)->applyEffects(m_activeInAnimationStack);
-    else if (m_activeInAnimationStack)
+        return const_cast<Animation*>(this)->applyEffects(m_activeInAnimationStack);
+
+    if (m_activeInAnimationStack) {
         const_cast<Animation*>(this)->clearEffects();
+        return true;
+    }
+    return false;
 }
 
 double Animation::calculateTimeToEffectChange(double inheritedTime, double activeTime, Phase phase) const
 {
     switch (phase) {
     case PhaseBefore:
         return activeTime - inheritedTime;
     case PhaseActive:
         return 0;
     case PhaseAfter:
         // If this Animation is still in effect then it will need to update
         // when its parent goes out of effect. We have no way of knowing when
         // that will be, however, so the parent will need to supply it.
         return std::numeric_limits<double>::infinity();
     case PhaseNone:
     default:
         ASSERT_NOT_REACHED();
         return 0;
     }
 }
 
 } // namespace WebCore