[Oilpan] Fix compile error on Oilpan after r362875

third_party/WebKit/Source/core/css/cssom/StyleValue.h

 #ifndef StyleValue_h
 #define StyleValue_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/CoreExport.h"
 #include "core/css/CSSValue.h"
 #include "core/css/CSSValuePool.h"
 
 namespace blink {
 
 class ScriptState;
 class ScriptValue;
 
 class CORE_EXPORT StyleValue : public RefCountedWillBeGarbageCollectedFinalized<StyleValue>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 
 public:
     enum StyleValueType {
         KeywordValueType, SimpleLengthType, CalcLengthType, NumberType
     };
 
     virtual StyleValueType type() const = 0;
 
     static PassRefPtrWillBeRawPtr<StyleValue> create(const CSSValue&);
     static ScriptValue parse(ScriptState*, const String& property, const String& cssText);
 
     virtual const String& cssString() const = 0;
     virtual PassRefPtrWillBeRawPtr<CSSValue> toCSSValue() = 0;
 
+    DEFINE_INLINE_VIRTUAL_TRACE() { }
+
 protected:
     StyleValue() {}
 };
 
 } // namespace blink
 
 #endif