rem: if (!this._feedButton) this._feedButton = document.getElementById("feed-button"); 
add: var feedButton = document.getElementById("feed-button"); if (!feedButton) return; 
context:   updateFeeds: function() {    if (!this._feedButton)      this._feedButton = document.getElementById("feed-button");    var feeds = gBrowser.mCurrentBrowser.feeds;    if (!feeds || feeds.length == 0) {      this._feedButton.removeAttribute("feeds");      this._feedButton.setAttribute("tooltiptext",                                     gNavigatorBundle.getString("feedNoFeeds"));    } else {      this._feedButton.setAttribute("feeds", "true");      this._feedButton.setAttribute("tooltiptext",                                     gNavigatorBundle.getString("feedHasFeeds"));    }  }, 
meta: 5459	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5459/d185bd2e555512f24ea5d82b4dd1c0fad0cb26eb/browser.js/clean/browser/base/content/browser.js