CSSValue Immediates: Replace CSSPrimitiveValue usage with const references

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 b4b20d0bf68c4c95d83e464a12cad33d4bdf0e41..0716d5b3ae5ed4063f7ad9158e363eeaad44dfad 100644
--- a/Source/core/css/StylePropertySet.h
+++ b/Source/core/css/StylePropertySet.h
@@ -70,9 +70,8 @@ public:
         bool isInherited() const { return propertyMetadata().m_inherited; }
         bool isImplicit() const { return propertyMetadata().m_implicit; }
 
-        const CSSValue value() const { return propertyValue(); }
         // FIXME: We should try to remove this mutable overload.
-        CSSValue value() { return propertyValue(); }
+        const CSSValue& value() { return propertyValue(); }
 
         // FIXME: Remove this.
         CSSProperty toCSSProperty() const { return CSSProperty(propertyMetadata(), propertyValue()); }
@@ -80,7 +79,7 @@ public:
         const StylePropertyMetadata& propertyMetadata() const;
 
     private:
-        const CSSValue propertyValue() const;
+        const CSSValue& propertyValue() const;
 
         const StylePropertySet& m_propertySet;
         unsigned m_index;
@@ -92,7 +91,7 @@ public:
     int findPropertyIndex(CSSPropertyID) const;
     bool hasProperty(CSSPropertyID property) const { return findPropertyIndex(property) != -1; }
 
-    NullableCSSValue getPropertyCSSValue(CSSPropertyID) const;
+    const NullableCSSValue getPropertyCSSValue(CSSPropertyID) const;
     String getPropertyValue(CSSPropertyID) const;
 
     bool propertyIsImportant(CSSPropertyID) const;
@@ -144,6 +143,7 @@ protected:
     unsigned m_arraySize : 28;
 
     friend class PropertySetCSSStyleDeclaration;
+
 };
 
 class CORE_EXPORT ImmutableStylePropertySet : public StylePropertySet {
@@ -256,7 +256,7 @@ inline const StylePropertyMetadata& StylePropertySet::PropertyReference::propert
     return toImmutableStylePropertySet(m_propertySet).metadataArray()[m_index];
 }
 
-inline const CSSValue StylePropertySet::PropertyReference::propertyValue() const
+inline const CSSValue& StylePropertySet::PropertyReference::propertyValue() const
 {
     if (m_propertySet.isMutable())
         return toMutableStylePropertySet(m_propertySet).m_propertyVector.at(m_index).value();