Adding @keyframes rules only affects TreeScope plus host.

third_party/WebKit/Source/core/animation/Animation.h

Index: third_party/WebKit/Source/core/animation/Animation.h
diff --git a/third_party/WebKit/Source/core/animation/Animation.h b/third_party/WebKit/Source/core/animation/Animation.h
index 72196c63012e11c6db1d1800bedb87c941984ec5..372d5272357bcf043dd0867f34c965c5501e3855 100644
--- a/third_party/WebKit/Source/core/animation/Animation.h
+++ b/third_party/WebKit/Source/core/animation/Animation.h
@@ -53,6 +53,7 @@ class AnimationTimeline;
 class CompositorAnimationPlayer;
 class Element;
 class ExceptionState;
+class TreeScope;
 
 class CORE_EXPORT Animation final
     : public EventTargetWithInlineData
@@ -182,7 +183,7 @@ public:
     bool effectSuppressed() const { return m_effectSuppressed; }
     void setEffectSuppressed(bool);
 
-    void invalidateKeyframeEffect();
+    void invalidateKeyframeEffect(const TreeScope&);
 
     DECLARE_VIRTUAL_TRACE();