Prevent GCs when constructing GC mixin objects.

Source/platform/heap/Handle.h

 /*
  * Copyright (C) 2014 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 28 matching lines @@
 #include "wtf/HashFunctions.h"
 #include "wtf/Locker.h"
 #include "wtf/RawPtr.h"
 #include "wtf/RefCounted.h"
 #include "wtf/TypeTraits.h"
 
 namespace blink {
 
 template<typename T> class HeapTerminatedArray;
 
-// Template to determine if a class is a GarbageCollectedMixin by checking if it
-// has IsGarbageCollectedMixinMarker
-template<typename T>
-struct IsGarbageCollectedMixin {
-private:
-    typedef char YesType;
-    struct NoType {
-        char padding[8];
-    };
-
-    template <typename U> static YesType checkMarker(typename U::IsGarbageCollectedMixinMarker*);
-    template <typename U> static NoType checkMarker(...);
-
-public:
-    static const bool value = sizeof(checkMarker<T>(nullptr)) == sizeof(YesType);
-};
-
 template <typename T>
 struct IsGarbageCollectedType {
     using TrueType = char;
     struct FalseType {
         char dummy[2];
     };
 
     using NonConstType = typename WTF::RemoveConst<T>::Type;
     using GarbageCollectedSubclass = WTF::IsSubclassOfTemplate<NonConstType, GarbageCollected>;
     using GarbageCollectedMixinSubclass = IsGarbageCollectedMixin<NonConstType>;
@@ skipping 1101 matching lines @@
 template<typename T>
 struct ParamStorageTraits<RawPtr<T>> : public PointerParamStorageTraits<T*, blink::IsGarbageCollectedType<T>::value> {
 };
 
 template<typename T>
 PassRefPtr<T> adoptRef(blink::RefCountedGarbageCollected<T>*) = delete;
 
 } // namespace WTF
 
 #endif