CSSValue Immediates: Change CSSValue to an object instead of a pointer

Source/core/style/StyleFetchedImage.cpp

Index: Source/core/style/StyleFetchedImage.cpp
diff --git a/Source/core/style/StyleFetchedImage.cpp b/Source/core/style/StyleFetchedImage.cpp
index f3cb2756955b44ad6944809baebc468f7276f10d..a0729b62a8f3d23bbf272126cdd12477efd416ae 100644
--- a/Source/core/style/StyleFetchedImage.cpp
+++ b/Source/core/style/StyleFetchedImage.cpp
@@ -44,7 +44,7 @@ StyleFetchedImage::~StyleFetchedImage()
     m_image->removeClient(this);
 }
 
-PassRefPtrWillBeRawPtr<CSSValue> StyleFetchedImage::cssValue() const
+NullableCSSValue StyleFetchedImage::cssValue() const
 {
     return CSSImageValue::create(m_image->url(), const_cast<StyleFetchedImage*>(this));
 }