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

third_party/WebKit/Source/core/xml/XPathNSResolver.idl

 /*
  * Copyright (C) 2006 Apple Computer, Inc.
  * Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
  *
  * 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 // http://www.w3.org/TR/DOM-Level-3-XPath/xpath.html#XPathNSResolver
 
 // TODO(philipj): XPathNSResolver should be a callback interface. The spec
 // doesn't say so, but doing so would allow the custom bindings to be removed.
 // createNSResolver(Node nodeResolver) could simply return its argument, which
 // is what Gecko does. crbug.com/345529
 
 [
-    GarbageCollected,
     NoInterfaceObject
 ] interface XPathNSResolver {
     DOMString? lookupNamespaceURI([Default=Undefined] optional DOMString prefix);
 };