Oilpan: disable conservative GCs during initial GC mixin construction.

Source/core/workers/SharedWorker.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2010 Apple 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.
@@ skipping 24 matching lines @@
 #include "core/workers/AbstractWorker.h"
 #include "platform/Supplementable.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class ExceptionState;
 
 class SharedWorker final : public AbstractWorker, public WillBeHeapSupplementable<SharedWorker> {
     DEFINE_WRAPPERTYPEINFO();
-    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(SharedWorker);
+    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN_NESTED(SharedWorker, AbstractWorker);
 public:
     static PassRefPtrWillBeRawPtr<SharedWorker> create(ExecutionContext*, const String& url, const String& name, ExceptionState&);
     virtual ~SharedWorker();
 
     MessagePort* port() const { return m_port.get(); }
 
     virtual const AtomicString& interfaceName() const override;
 
     void setIsBeingConnected(bool b) { m_isBeingConnected = b; }
 
     virtual bool hasPendingActivity() const override;
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     explicit SharedWorker(ExecutionContext*);
 
     RefPtrWillBeMember<MessagePort> m_port;
     bool m_isBeingConnected;
 };
 
 } // namespace blink
 
 #endif // SharedWorker_h