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..b8586b9810590e2d31d792547c04b01cd044ce89 100644
--- a/Source/core/css/StylePropertySet.h
+++ b/Source/core/css/StylePropertySet.h
@@ -70,9 +70,7 @@ 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() const { return propertyValue(); }
 
         // FIXME: Remove this.
         CSSProperty toCSSProperty() const { return CSSProperty(propertyMetadata(), propertyValue()); }
@@ -80,7 +78,7 @@ public:
         const StylePropertyMetadata& propertyMetadata() const;
 
     private:
-        const CSSValue propertyValue() const;
+        const CSSValue& propertyValue() const;
 
         const StylePropertySet& m_propertySet;
         unsigned m_index;
@@ -196,7 +194,7 @@ public:
 
     // These expand shorthand properties into multiple properties.
     bool setProperty(CSSPropertyID unresolvedProperty, const String& value, bool important = false, StyleSheetContents* contextStyleSheet = 0);
-    void setProperty(CSSPropertyID, CSSValue, bool important = false);
+    void setProperty(CSSPropertyID, const CSSValue&, bool important = false);
     void setProperty(CSSPropertyID, CSSPrimitiveValue, bool important = false);
 
     // These do not. FIXME: This is too messy, we can do better.
@@ -256,7 +254,7 @@ 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();