Update animation when changes in animation keyframes are detected.

Source/core/css/CSSKeyframesRule.h

 /*
  * Copyright (C) 2007, 2008, 2012 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 43 matching lines @@
 
     bool isVendorPrefixed() const { return m_isPrefixed; }
     void setVendorPrefixed(bool isPrefixed) { m_isPrefixed = isPrefixed; }
 
     int findKeyframeIndex(const String& key) const;
 
     PassRefPtrWillBeRawPtr<StyleRuleKeyframes> copy() const { return adoptRefWillBeNoop(new StyleRuleKeyframes(*this)); }
 
     void traceAfterDispatch(Visitor*);
 
+    void styleChanged() { m_styleChangeCounter++; }
+    unsigned styleChangeCounter() const { return m_styleChangeCounter; }
+
 private:
     StyleRuleKeyframes();
     explicit StyleRuleKeyframes(const StyleRuleKeyframes&);
 
     WillBeHeapVector<RefPtrWillBeMember<StyleRuleKeyframe> > m_keyframes;
     AtomicString m_name;
     bool m_isPrefixed;
+    unsigned m_styleChangeCounter;
 };
 
 DEFINE_STYLE_RULE_TYPE_CASTS(Keyframes);
 
 class CSSKeyframesRule final : public CSSRule {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static PassRefPtrWillBeRawPtr<CSSKeyframesRule> create(StyleRuleKeyframes* rule, CSSStyleSheet* sheet)
     {
         return adoptRefWillBeNoop(new CSSKeyframesRule(rule, sheet));
@@ skipping 24 matching lines @@
 
 private:
     CSSKeyframesRule(StyleRuleKeyframes*, CSSStyleSheet* parent);
 
     virtual CSSRule::Type type() const override { return KEYFRAMES_RULE; }
 
     RefPtrWillBeMember<StyleRuleKeyframes> m_keyframesRule;
     mutable WillBeHeapVector<RefPtrWillBeMember<CSSKeyframeRule> > m_childRuleCSSOMWrappers;
     mutable OwnPtrWillBeMember<CSSRuleList> m_ruleListCSSOMWrapper;
     bool m_isPrefixed;
+
+    friend class CSSKeyframeRule;
 };
 
 DEFINE_CSS_RULE_TYPE_CASTS(CSSKeyframesRule, KEYFRAMES_RULE);
 
 } // namespace blink
 
 #endif // CSSKeyframesRule_h