Add missing traces for Supplement<> classes

third_party/WebKit/Source/platform/Supplementable.h

 /*
  * Copyright (C) 2012 Google, Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 89 matching lines @@
 
     static Supplement<T>* from(Supplementable<T>& host, const char* key)
     {
         return host.requireSupplement(key);
     }
 
     static Supplement<T>* from(Supplementable<T>* host, const char* key)
     {
         return host ? host->requireSupplement(key) : 0;
     }
+
+    DEFINE_INLINE_VIRTUAL_TRACE() { }
 };
 
 // Supplementable<T> inherits from GarbageCollectedMixin virtually
 // to allow ExecutionContext to derive from two GC mixin classes.
 template<typename T>
 class Supplementable : public virtual GarbageCollectedMixin {
     WTF_MAKE_NONCOPYABLE(Supplementable);
 public:
     void provideSupplement(const char* key, Supplement<T>* supplement)
     {
@@ skipping 49 matching lines @@
 };
 
 template<typename T>
 struct ThreadingTrait<Supplementable<T>> {
     static const ThreadAffinity Affinity = ThreadingTrait<T>::Affinity;
 };
 
 } // namespace blink
 
 #endif // Supplementable_h