add:  gBrowser.mCurrentBrowser.engines = null;  
context:   startDocumentLoad : function(aRequest)  {    // It's okay to clear what the user typed when we start    // loading a document. If the user types, this counter gets    // set to zero, if the document load ends without an    // onLocationChange, this counter gets decremented    // (so we keep it while switching tabs after failed loads)    getBrowser().userTypedClear++;    // clear out feed data    gBrowser.mCurrentBrowser.feeds = null;    const nsIChannel = Components.interfaces.nsIChannel;    var urlStr = aRequest.QueryInterface(nsIChannel).URI.spec;    var observerService = Components.classes["@mozilla.org/observer-service;1"]                                    .getService(Components.interfaces.nsIObserverService);    try {      observerService.notifyObservers(content, "StartDocumentLoad", urlStr);    } catch (e) {    }  },
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/53f781ee795b039e263be4d6baf8d240add41937/browser.js/buggy/browser/base/content/browser.js