CSSValue Immediates: Replace CSSValue usage with const references

Source/core/css/CSSProperty.h

Index: Source/core/css/CSSProperty.h
diff --git a/Source/core/css/CSSProperty.h b/Source/core/css/CSSProperty.h
index 2a2230055f81dacee3e0a6a7f747c3114efe399d..5cd76b1e3fde1b4cff51b585e7412d6d97caaf0a 100644
--- a/Source/core/css/CSSProperty.h
+++ b/Source/core/css/CSSProperty.h
@@ -56,14 +56,14 @@ struct StylePropertyMetadata {
 class CSSProperty {
     ALLOW_ONLY_INLINE_ALLOCATION();
 public:
-    CSSProperty(CSSPropertyID propertyID, CSSValue value, bool important = false, bool isSetFromShorthand = false, int indexInShorthandsVector = 0, bool implicit = false)
+    CSSProperty(CSSPropertyID propertyID, const CSSValue& value, bool important = false, bool isSetFromShorthand = false, int indexInShorthandsVector = 0, bool implicit = false)
         : m_metadata(propertyID, isSetFromShorthand, indexInShorthandsVector, important, implicit, CSSPropertyMetadata::isInheritedProperty(propertyID))
         , m_value(value)
     {
     }
 
     // FIXME: Remove this.
-    CSSProperty(StylePropertyMetadata metadata, CSSValue value)
+    CSSProperty(StylePropertyMetadata metadata, const CSSValue& value)
         : m_metadata(metadata)
         , m_value(value)
     {