Make ActiveScriptWrappable the GC mixin it is.

third_party/WebKit/Source/core/html/HTMLImageElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 25 matching lines @@
 
 namespace blink {
 
 class HTMLFormElement;
 class ImageCandidate;
 class ShadowRoot;
 class ImageBitmapOptions;
 
 class CORE_EXPORT HTMLImageElement final : public HTMLElement, public CanvasImageSource, public ImageBitmapSource, public ActiveScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
+    USING_GARBAGE_COLLECTED_MIXIN(HTMLImageElement);
 public:
     class ViewportChangeListener;
 
     static HTMLImageElement* create(Document&);
     static HTMLImageElement* create(Document&, HTMLFormElement*, bool createdByParser);
     static HTMLImageElement* createForJSConstructor(Document&);
     static HTMLImageElement* createForJSConstructor(Document&, int width);
     static HTMLImageElement* createForJSConstructor(Document&, int width, int height);
 
     ~HTMLImageElement() override;
@@ skipping 113 matching lines @@
     unsigned m_elementCreatedByParser : 1;
     unsigned m_useFallbackContent : 1;
     unsigned m_isFallbackImage : 1;
 
     ReferrerPolicy m_referrerPolicy;
 };
 
 } // namespace blink
 
 #endif // HTMLImageElement_h