CSSValue Immediates: Make CSSPrimitiveValue a container

Source/core/css/CSSCrossfadeValue.h

Index: Source/core/css/CSSCrossfadeValue.h
diff --git a/Source/core/css/CSSCrossfadeValue.h b/Source/core/css/CSSCrossfadeValue.h
index 7d581ea976af58a089587b6bd926bda746502497..d92841794edb62c36f8e880c2e6fbe9eda194909 100644
--- a/Source/core/css/CSSCrossfadeValue.h
+++ b/Source/core/css/CSSCrossfadeValue.h
@@ -60,7 +60,7 @@ public:
 
     void loadSubimages(Document*);
 
-    void setPercentage(PassRefPtrWillBeRawPtr<CSSPrimitiveValue> percentageValue) { m_percentageValue = percentageValue; }
+    void setPercentage(CSSPrimitiveValue percentageValue) { m_percentageValue = percentageValue; }
 
     bool hasFailedOrCanceledSubresources() const;
 
@@ -100,7 +100,7 @@ private:
 
     CSSValue m_fromValue;
     CSSValue m_toValue;
-    RefPtrWillBeMember<CSSPrimitiveValue> m_percentageValue;
+    NullableCSSValue m_percentageValue;
 
     ResourcePtr<ImageResource> m_cachedFromImage;
     ResourcePtr<ImageResource> m_cachedToImage;