Revert of Revert of Implement unset value handling

Source/core/css/CSSValuePool.h

 /*
  * Copyright (C) 2011, 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 13 matching lines @@
  */
 
 #ifndef CSSValuePool_h
 #define CSSValuePool_h
 
 #include "core/CSSPropertyNames.h"
 #include "core/CSSValueKeywords.h"
 #include "core/css/CSSInheritedValue.h"
 #include "core/css/CSSInitialValue.h"
 #include "core/css/CSSPrimitiveValue.h"
+#include "core/css/CSSUnsetValue.h"
 #include "wtf/HashMap.h"
 #include "wtf/RefPtr.h"
 #include "wtf/text/AtomicStringHash.h"
 
 namespace blink {
 
 class CSSValueList;
 
 class CSSValuePool :  public NoBaseWillBeGarbageCollected<CSSValuePool> {
     WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED;
 public:
     PassRefPtrWillBeRawPtr<CSSValueList> createFontFaceValue(const AtomicString&);
     PassRefPtrWillBeRawPtr<CSSPrimitiveValue> createFontFamilyValue(const String&);
     PassRefPtrWillBeRawPtr<CSSInheritedValue> createInheritedValue() { return m_inheritedValue; }
     PassRefPtrWillBeRawPtr<CSSInitialValue> createImplicitInitialValue() { return m_implicitInitialValue; }
     PassRefPtrWillBeRawPtr<CSSInitialValue> createExplicitInitialValue() { return m_explicitInitialValue; }
+    PassRefPtrWillBeRawPtr<CSSUnsetValue> createUnsetValue() { return m_unsetValue; }
     PassRefPtrWillBeRawPtr<CSSPrimitiveValue> createIdentifierValue(CSSValueID identifier);
     PassRefPtrWillBeRawPtr<CSSPrimitiveValue> createIdentifierValue(CSSPropertyID identifier);
     PassRefPtrWillBeRawPtr<CSSPrimitiveValue> createColorValue(unsigned rgbValue);
     PassRefPtrWillBeRawPtr<CSSPrimitiveValue> createValue(double value, CSSPrimitiveValue::UnitType);
     PassRefPtrWillBeRawPtr<CSSPrimitiveValue> createValue(const String& value, CSSPrimitiveValue::UnitType type) { return CSSPrimitiveValue::create(value, type); }
     PassRefPtrWillBeRawPtr<CSSPrimitiveValue> createValue(const Length& value, const RenderStyle&);
     PassRefPtrWillBeRawPtr<CSSPrimitiveValue> createValue(const Length& value, float zoom) { return CSSPrimitiveValue::create(value, zoom); }
     template<typename T> static PassRefPtrWillBeRawPtr<CSSPrimitiveValue> createValue(T value) { return CSSPrimitiveValue::create(value); }
 
     void trace(Visitor*);
 
 private:
     CSSValuePool();
 
     RefPtrWillBeMember<CSSInheritedValue> m_inheritedValue;
     RefPtrWillBeMember<CSSInitialValue> m_implicitInitialValue;
     RefPtrWillBeMember<CSSInitialValue> m_explicitInitialValue;
+    RefPtrWillBeMember<CSSUnsetValue> m_unsetValue;
 
     WillBeHeapVector<RefPtrWillBeMember<CSSPrimitiveValue>, numCSSValueKeywords> m_identifierValueCache;
 
     typedef WillBeHeapHashMap<unsigned, RefPtrWillBeMember<CSSPrimitiveValue> > ColorValueCache;
     ColorValueCache m_colorValueCache;
     RefPtrWillBeMember<CSSPrimitiveValue> m_colorTransparent;
     RefPtrWillBeMember<CSSPrimitiveValue> m_colorWhite;
     RefPtrWillBeMember<CSSPrimitiveValue> m_colorBlack;
 
     static const int maximumCacheableIntegerValue = 255;
 
     WillBeHeapVector<RefPtrWillBeMember<CSSPrimitiveValue>, maximumCacheableIntegerValue + 1> m_pixelValueCache;
     WillBeHeapVector<RefPtrWillBeMember<CSSPrimitiveValue>, maximumCacheableIntegerValue + 1> m_percentValueCache;
     WillBeHeapVector<RefPtrWillBeMember<CSSPrimitiveValue>, maximumCacheableIntegerValue + 1> m_numberValueCache;
 
     typedef WillBeHeapHashMap<AtomicString, RefPtrWillBeMember<CSSValueList> > FontFaceValueCache;
     FontFaceValueCache m_fontFaceValueCache;
 
     typedef WillBeHeapHashMap<String, RefPtrWillBeMember<CSSPrimitiveValue> > FontFamilyValueCache;
     FontFamilyValueCache m_fontFamilyValueCache;
 
     friend CSSValuePool& cssValuePool();
 };
 
 CSSValuePool& cssValuePool();
 
 }
 
 #endif