Adding @keyframes rules only affects TreeScope plus host.

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 72 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 invalidateKeyframeEffects();
+    void invalidateKeyframeEffects(const TreeScope&);
 
     void setPlaybackRate(double);
     double playbackRate() const;
 
     CompositorAnimationTimeline* compositorTimeline() const { return m_compositorTimeline.get(); }
 
     Document* document() { return m_document.get(); }
     void wake();
     void resetForTesting();
 
@@ skipping 42 matching lines @@
         Member<AnimationTimeline> m_timeline;
         Timer<AnimationTimelineTiming> m_timer;
     };
 
     friend class AnimationAnimationTimelineTest;
 };
 
 } // namespace blink
 
 #endif