Improve DEFINE_STATIC_LOCAL()'s handling of Blink GCed objects.

third_party/WebKit/Source/core/css/CSSPathValue.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 CSSPathValue_h
 #define CSSPathValue_h
 
 #include "core/css/CSSValue.h"
 #include "core/style/StylePath.h"
 #include "core/svg/SVGPathByteStream.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefPtr.h"
 
 namespace blink {
 
 class StylePath;
 
 class CSSPathValue : public CSSValue {
 public:
     static RawPtr<CSSPathValue> create(PassRefPtr<StylePath>);
     static RawPtr<CSSPathValue> create(PassOwnPtr<SVGPathByteStream>);
 
-    static CSSPathValue* emptyPathValue();
+    static CSSPathValue& emptyPathValue();
 
     StylePath* stylePath() const { return m_stylePath.get(); }
     String customCSSText() const;
 
     bool equals(const CSSPathValue&) const;
 
     DECLARE_TRACE_AFTER_DISPATCH();
 
     const SVGPathByteStream& byteStream() const { return m_stylePath->byteStream(); }
 
 private:
     CSSPathValue(PassRefPtr<StylePath>);
 
     RefPtr<StylePath> m_stylePath;
 };
 
 DEFINE_CSS_VALUE_TYPE_CASTS(CSSPathValue, isPathValue());
 
 } // namespace blink
 
 #endif // CSSPathValue_h