Partial implementation of CSSVariablesMap for CSS Variables CSSOM

Source/core/css/StylePropertySet.h

Index: Source/core/css/StylePropertySet.h
diff --git a/Source/core/css/StylePropertySet.h b/Source/core/css/StylePropertySet.h
index 3fed4302f2db09da3ccb9aca97bd3c3cb4db6ddb..ba4304b1190a89137d64a905a26d1daa8465e24b 100644
--- a/Source/core/css/StylePropertySet.h
+++ b/Source/core/css/StylePropertySet.h
@@ -85,9 +85,13 @@ public:
     bool isEmpty() const;
     PropertyReference propertyAt(unsigned index) const { return PropertyReference(*this, index); }
     int findPropertyIndex(CSSPropertyID) const;
+    size_t findVariableIndex(const AtomicString& name) const;
 
     PassRefPtr<CSSValue> getPropertyCSSValue(CSSPropertyID) const;
     String getPropertyValue(CSSPropertyID) const;
+    unsigned variableCount() const;
+    String variableValue(const AtomicString& name) const;
+
     bool propertyIsImportant(CSSPropertyID) const;
     CSSPropertyID getPropertyShorthand(CSSPropertyID) const;
     bool isPropertyImplicit(CSSPropertyID) const;
@@ -197,6 +201,7 @@ public:
     void appendPrefixingVariantProperty(const CSSProperty&);
     void setPrefixingVariantProperty(const CSSProperty&);
     void setProperty(const CSSProperty&, CSSProperty* slot = 0);
+    bool setVariableValue(const AtomicString& name, const String& value, bool important = false);
 
     bool removeProperty(CSSPropertyID, String* returnText = 0);
     void removePrefixedOrUnprefixedProperty(CSSPropertyID);
@@ -204,6 +209,8 @@ public:
     bool removePropertiesInSet(const CSSPropertyID* set, unsigned length);
     void removeEquivalentProperties(const StylePropertySet*);
     void removeEquivalentProperties(const CSSStyleDeclaration*);
+    bool removeVariable(const AtomicString& name);
+    bool clearVariables();
 
     void mergeAndOverrideOnConflict(const StylePropertySet*);