add: return null; 
context: function enterNewSite(site) {  var promptService = Components.classes["@mozilla.org/embedcomp/prompt-service;1"]                              .getService(Components.interfaces.nsIPromptService);  var stringBundle = document.getElementById("stringBundle");  var message = stringBundle.getString("enterSiteName");  var title = stringBundle.getString("enterSiteTitle");  var name = (!site ? {} : site);  if (!promptService.prompt(window, title, message, name, null, {}))      return;  var host = name.value.replace(/^\s*([-\w]*:\/+)?/, ""); // trim any leading space and scheme  try {    var ioService = Components.classes["@mozilla.org/network/io-service;1"]                              .getService(Components.interfaces.nsIIOService);    var uri = ioService.newURI("http://"+host, null, null);    host = uri.host;    return host;  } catch(ex) {    // if we get here, the user has managed to enter something that couldn't get parsed to a real URI    // call this function again, with the string originally entered pre-populated    var alertTitle = stringBundle.getString("addSiteFailedTitle");    var alertMsg = stringBundle.getFormattedString("addSiteFailedMessage",[host]);    promptService.alert(window, alertTitle, alertMsg);    enterNewSite(name);  }}
meta: 10234	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/10234/37c6d45bcacd11c551a5597610b1b1997c42ccff/pref-features.js/clean/browser/components/prefwindow/content/pref-features.js