Move Image ownership out of CSSValue

Source/core/css/parser/CSSPropertyParser.cpp

Index: Source/core/css/parser/CSSPropertyParser.cpp
diff --git a/Source/core/css/parser/CSSPropertyParser.cpp b/Source/core/css/parser/CSSPropertyParser.cpp
index 97a4ff398ce4e3c4787bd9dd8998cc73717b8e48..9627946b0711917ae4e2a91394f7a2c0bb591cac 100644
--- a/Source/core/css/parser/CSSPropertyParser.cpp
+++ b/Source/core/css/parser/CSSPropertyParser.cpp
@@ -316,8 +316,8 @@ inline PassRefPtrWillBeRawPtr<CSSPrimitiveValue> CSSPropertyParser::createPrimit
 
 inline PassRefPtrWillBeRawPtr<CSSValue> CSSPropertyParser::createCSSImageValueWithReferrer(const String& rawValue, const KURL& url)
 {
-    RefPtrWillBeRawPtr<CSSValue> imageValue = CSSImageValue::create(rawValue, url);
-    toCSSImageValue(imageValue.get())->setReferrer(m_context.referrer());
+    RefPtrWillBeRawPtr<CSSImageValue> imageValue = CSSImageValue::create(rawValue, url);
+    imageValue->setReferrer(m_context.referrer());
     return imageValue;
 }