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

Source/core/css/ComputedStyleCSSValueMapping.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ComputedStyleCSSValueMapping_h
 #define ComputedStyleCSSValueMapping_h
 
 #include "core/CSSPropertyNames.h"
 #include "core/css/CSSValue.h"
 
 namespace blink {
 
 class CSSPrimitiveValue;
 class LayoutObject;
 class ComputedStyle;
 class ShadowData;
 class ShadowList;
 class StyleColor;
 class Node;
 
 class ComputedStyleCSSValueMapping {
 public:
     // FIXME: Resolve computed auto alignment in applyProperty/ComputedStyle and remove this non-const styledNode parameter.
-    static PassRefPtrWillBeRawPtr<CSSValue> get(CSSPropertyID, const ComputedStyle&, const LayoutObject* = nullptr, Node* styledNode = nullptr, bool allowVisitedStyle = false);
+    static NullableCSSValue get(CSSPropertyID, const ComputedStyle&, const LayoutObject* = nullptr, Node* styledNode = nullptr, bool allowVisitedStyle = false);
 private:
     static PassRefPtrWillBeRawPtr<CSSPrimitiveValue> currentColorOrValidColor(const ComputedStyle&, const StyleColor&);
-    static PassRefPtrWillBeRawPtr<CSSValue> valueForShadowData(const ShadowData&, const ComputedStyle&, bool useSpread);
-    static PassRefPtrWillBeRawPtr<CSSValue> valueForShadowList(const ShadowList*, const ComputedStyle&, bool useSpread);
-    static PassRefPtrWillBeRawPtr<CSSValue> valueForFilter(const ComputedStyle&);
-    static PassRefPtrWillBeRawPtr<CSSValue> valueForFont(const ComputedStyle&);
+    static CSSValue valueForShadowData(const ShadowData&, const ComputedStyle&, bool useSpread);
+    static CSSValue valueForShadowList(const ShadowList*, const ComputedStyle&, bool useSpread);
+    static CSSValue valueForFilter(const ComputedStyle&);
+    static CSSValue valueForFont(const ComputedStyle&);
 };
 
 } // namespace blink
 
 #endif // ComputedStyleCSSValueMapping_h