Adding @keyframes rules only affects TreeScope plus host.

third_party/WebKit/Source/core/animation/Animation.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 35 matching lines @@
 #include "platform/heap/Handle.h"
 #include "wtf/RefPtr.h"
 #include <memory>
 
 namespace blink {
 
 class AnimationTimeline;
 class CompositorAnimationPlayer;
 class Element;
 class ExceptionState;
+class TreeScope;
 
 class CORE_EXPORT Animation final
     : public EventTargetWithInlineData
     , public ActiveScriptWrappable
     , public ActiveDOMObject
     , public CompositorAnimationDelegate
     , public CompositorAnimationPlayerClient {
     DEFINE_WRAPPERTYPEINFO();
     USING_GARBAGE_COLLECTED_MIXIN(Animation);
     USING_PRE_FINALIZER(Animation, dispose);
@@ skipping 109 matching lines @@
     int compositorGroup() const { return m_compositorGroup; }
 
     static bool hasLowerPriority(const Animation* animation1, const Animation* animation2)
     {
         return animation1->sequenceNumber() < animation2->sequenceNumber();
     }
 
     bool effectSuppressed() const { return m_effectSuppressed; }
     void setEffectSuppressed(bool);
 
-    void invalidateKeyframeEffect();
+    void invalidateKeyframeEffect(const TreeScope&);
 
     DECLARE_VIRTUAL_TRACE();
 
 protected:
     DispatchEventResult dispatchEventInternal(Event*) override;
     void addedEventListener(const AtomicString& eventType, RegisteredEventListener&) override;
 
 private:
     Animation(ExecutionContext*, AnimationTimeline&, AnimationEffectReadOnly*);
 
@@ skipping 111 matching lines @@
 
     bool m_currentTimePending;
     bool m_stateIsBeingUpdated;
 
     bool m_effectSuppressed;
 };
 
 } // namespace blink
 
 #endif // Animation_h