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

third_party/WebKit/Source/core/xml/XPathEvaluator.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#XPathEvaluator
 
 // Note: The spec says "the XPathEvaluator interface will be implemented on the
 // same object which implements the Document interface" and does not define a
 // constructor or other means to create an XPathEvaluator object. Nonetheless,
 // Blink, Gecko, Presto, WebKit and all have these APIs on both Document and the
 // constructable XPathEvaluator interface.
 
 [
     Constructor,
-    GarbageCollected,
     Measure,
 ] interface XPathEvaluator {
     [Measure, RaisesException] XPathExpression createExpression(DOMString expression, optional XPathNSResolver? resolver = null);
 
     [Measure] XPathNSResolver createNSResolver(Node nodeResolver);
 
     [Measure, RaisesException] XPathResult evaluate(DOMString expression, Node contextNode, optional XPathNSResolver? resolver = null, optional unsigned short type = 0, optional object? inResult = null);
 };