Have bindings layer assume and insist that all interface types are GCed.

third_party/WebKit/Source/core/testing/Internals.idl

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 Apple Inc. All rights reserved.
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  * modification, are permitted provided that the following conditions
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 [
     DoNotCheckConstants,
-    GarbageCollected,
     ConstructorCallWith=ScriptState,
 ] interface Internals {
     DOMString address(Node node);
 
     GCObservation observeGC(any observed);
 
     [RaisesException] DOMString elementLayoutTreeAsText(Element element);
     boolean isPreloaded(DOMString url);
     boolean isPreloadedBy(DOMString url, Document document);
     boolean isLoadingFromMemoryCache(DOMString url);
@@ skipping 315 matching lines @@
 
     void setMediaElementNetworkState(HTMLMediaElement element, long state);
 
     // TODO(liberato): remove once autoplay gesture override experiment concludes.
     void triggerAutoplayViewportCheck(HTMLMediaElement mediaElement);
 
     DOMString getScrollAnimationState(Node node);
 
     DOMString getProgrammaticScrollAnimationState(Node node);
 };