add: return null; 
context:   QueryInterface : function(iid)  {    if(iid.equals(Components.interfaces.nsIXULBrowserWindow))      return this;    throw Components.results.NS_NOINTERFACE;  },
meta: 10234	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/10234/e3f8c0039e4ff935493082c1f45e6436d8ed9f83/navigator.js/clean/xpfe/browser/resources/content/navigator.js