Adding @keyframes rules only affects TreeScope plus host.

third_party/WebKit/Source/core/dom/StyleEngine.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
@@ skipping 110 matching lines @@
 
     bool usesRemUnits() const { return m_usesRemUnits; }
     void setUsesRemUnit(bool b) { m_usesRemUnits = b; }
 
     void resetCSSFeatureFlags(const RuleFeatureSet&);
 
     void didRemoveShadowRoot(ShadowRoot*);
     void shadowRootRemovedFromDocument(ShadowRoot*);
     void appendActiveAuthorStyleSheets();
 
-    void setHasUnresolvedKeyframesRule() { m_hasUnresolvedKeyframesRule = true; }
-    void keyframesRulesAdded();
-
     StyleResolver* resolver() const
     {
         return m_resolver.get();
     }
 
     StyleResolver& ensureResolver()
     {
         if (!m_resolver) {
             createResolver();
         } else if (m_resolver->hasPendingAuthorStyleSheets()) {
@@ skipping 117 matching lines @@
     String m_selectedStylesheetSetName;
 
     bool m_usesSiblingRules = false;
     bool m_usesFirstLineRules = false;
     bool m_usesWindowInactiveSelector = false;
     bool m_usesRemUnits = false;
     unsigned m_maxDirectAdjacentSelectors = 0;
 
     bool m_ignorePendingStylesheets = false;
     bool m_didCalculateResolver = false;
-    bool m_hasUnresolvedKeyframesRule = false;
 
     Member<StyleResolver> m_resolver;
     StyleInvalidator m_styleInvalidator;
 
     Member<CSSFontSelector> m_fontSelector;
 
     HeapHashMap<AtomicString, WeakMember<StyleSheetContents>> m_textToSheetCache;
     HeapHashMap<WeakMember<StyleSheetContents>, AtomicString> m_sheetToTextCache;
 
     std::unique_ptr<StyleResolverStats> m_styleResolverStats;
     unsigned m_styleForElementCount = 0;
 
     friend class StyleEngineTest;
 };
 
 } // namespace blink
 
 #endif