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

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

 /*
  * Copyright (C) 2006 Apple Computer, Inc.
  *
  * 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#XPathResult
 
 [
-    GarbageCollected
 ] interface XPathResult {
     // XPathResultType
     const unsigned short ANY_TYPE                       = 0;
     const unsigned short NUMBER_TYPE                    = 1;
     const unsigned short STRING_TYPE                    = 2;
     const unsigned short BOOLEAN_TYPE                   = 3;
     const unsigned short UNORDERED_NODE_ITERATOR_TYPE   = 4;
     const unsigned short ORDERED_NODE_ITERATOR_TYPE     = 5;
     const unsigned short UNORDERED_NODE_SNAPSHOT_TYPE   = 6;
     const unsigned short ORDERED_NODE_SNAPSHOT_TYPE     = 7;
     const unsigned short ANY_UNORDERED_NODE_TYPE        = 8;
     const unsigned short FIRST_ORDERED_NODE_TYPE        = 9;
 
     readonly attribute unsigned short  resultType;
     [RaisesException=Getter] readonly attribute double          numberValue;
 
     [RaisesException=Getter] readonly attribute DOMString       stringValue;
 
     [RaisesException=Getter] readonly attribute boolean         booleanValue;
 
     [RaisesException=Getter] readonly attribute Node            singleNodeValue;
 
     readonly attribute boolean         invalidIteratorState;
     [RaisesException=Getter] readonly attribute unsigned long   snapshotLength;
 
     [RaisesException] Node? iterateNext();
     [RaisesException] Node? snapshotItem(unsigned long index);
 };