Add fast-path for propagated variable changes (WIP)

third_party/WebKit/Source/core/css/CSSVariableData.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CSSVariableData_h
 #define CSSVariableData_h
 
 #include "core/css/StylePropertySet.h"
 #include "core/css/parser/CSSParserToken.h"
 #include "core/css/parser/CSSParserTokenRange.h"
@@ skipping 24 matching lines @@
       bool isAnimationTainted) {
     return adoptRef(new CSSVariableData(
         resolvedTokens, unresolvedData.m_backingString, isAnimationTainted));
   }
 
   CSSParserTokenRange tokenRange() const { return m_tokens; }
 
   const Vector<CSSParserToken>& tokens() const { return m_tokens; }
 
   bool operator==(const CSSVariableData& other) const;
+  bool operator!=(const CSSVariableData& other) const {
+    return !(*this == other);
+  }
 
   bool isAnimationTainted() const { return m_isAnimationTainted; }
 
   bool needsVariableResolution() const { return m_needsVariableResolution; }
 
   const CSSValue* parseForSyntax(const CSSSyntaxDescriptor&) const;
 
   StylePropertySet* propertySet();
 
  private:
@@ skipping 25 matching lines @@
   const bool m_needsVariableResolution;
 
   // Parsed representation for @apply
   bool m_cachedPropertySet;
   Persistent<StylePropertySet> m_propertySet;
 };
 
 }  // namespace blink
 
 #endif  // CSSVariableData_h