CSSValue Immediates: Replace CSSPrimitiveValue usage with const references

Source/core/css/StylePropertySerializer.h

Index: Source/core/css/StylePropertySerializer.h
diff --git a/Source/core/css/StylePropertySerializer.h b/Source/core/css/StylePropertySerializer.h
index 310e1b4aec0ac6e0e1f9c457f65732f122ae00ff..17f1cf77a28c73d18cf822eae42e00148136c57c 100644
--- a/Source/core/css/StylePropertySerializer.h
+++ b/Source/core/css/StylePropertySerializer.h
@@ -58,14 +58,14 @@ private:
     // Only StylePropertySerializer uses the following two classes.
     class PropertyValueForSerializer {
     public:
-        explicit PropertyValueForSerializer(StylePropertySet::PropertyReference property)
+        explicit PropertyValueForSerializer(const StylePropertySet::PropertyReference& property)
             : m_value(property.value())
             , m_id(property.id())
             , m_isImportant(property.isImportant())
             , m_isImplicit(property.isImplicit())
             , m_isInherited(property.isInherited()) { }
 
-        PropertyValueForSerializer(CSSPropertyID id, const CSSValue value, bool isImportant)
+        PropertyValueForSerializer(CSSPropertyID id, const CSSValue& value, bool isImportant)
             : m_value(value)
             , m_id(id)
             , m_isImportant(isImportant)