Optimize style recalc when adding @keyframes.

third_party/WebKit/Source/core/animation/AnimationTimeline.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 73 matching lines @@
     void setCurrentTime(double);
     void setCurrentTimeInternal(double);
     double effectiveTime();
     void pauseAnimationsForTesting(double);
 
     void setAllCompositorPending(bool sourceChanged = false);
     void setOutdatedAnimation(Animation*);
     void clearOutdatedAnimation(Animation*);
     bool hasOutdatedAnimation() const { return m_outdatedAnimationCount > 0; }
     bool needsAnimationTimingUpdate();
+    void setHasUnresolvedKeyframesRule() { m_hasUnresolvedKeyframesRule = true; }
+    void keyframesRulesAdded();
 
     void setPlaybackRate(double);
     double playbackRate() const;
 
     CompositorAnimationTimeline* compositorTimeline() const { return m_compositorTimeline.get(); }
 
     Document* document() { return m_document.get(); }
     void wake();
     void resetForTesting();
 
     DECLARE_TRACE();
 
 protected:
     AnimationTimeline(Document*, PlatformTiming*);
 
 private:
     Member<Document> m_document;
     double m_zeroTime;
     bool m_zeroTimeInitialized;
+    bool m_hasUnresolvedKeyframesRule;

[alancutter (OOO until 2018), 2016/06/29 03:41:32]

Could this live on Document instead? I don't think CSS specific concepts should
live on the AnimationTimeline.

[alancutter (OOO until 2018), 2016/06/29 08:10:21]

One option to keep it scoped to animations is to make DocumentAnimation a member
of Document and put it in there.

     unsigned m_outdatedAnimationCount;
     // Animations which will be updated on the next frame
     // i.e. current, in effect, or had timing changed
     HeapHashSet<Member<Animation>> m_animationsNeedingUpdate;
     HeapHashSet<WeakMember<Animation>> m_animations;
 
     double m_playbackRate;
 
     friend class SMILTimeContainer;
     static const double s_minimumDelay;
@@ skipping 23 matching lines @@
         Member<AnimationTimeline> m_timeline;
         Timer<AnimationTimelineTiming> m_timer;
     };
 
     friend class AnimationAnimationTimelineTest;
 };
 
 } // namespace blink
 
 #endif