rem: var shell = findChildShell(doc, browsers[i].docShell, feedURI); 
add: var shell = findChildShell(doc, browsers[i].docShell, null); 
context:   _getContentShell: function(doc, feedURI) {    var browsers = getBrowser().browsers;    for (var i = 0; i < browsers.length; i++) {      var shell = findChildShell(doc, browsers[i].docShell, feedURI);      if (shell)        return { shell: shell, browser: browsers[i] };    }    return null;  },
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/0c069551201c44cd92a1a0e08557520fc75094ef/browser.js/buggy/browser/base/content/browser.js