add: if (!gURLBar.value) return;  
context: function handleURLBarCommand(aTriggeringEvent) {  var postData = { };  canonizeUrl(aTriggeringEvent, postData);  try {    addToUrlbarHistory(gURLBar.value);  } catch (ex) {    // Things may go wrong when adding url to session history,    // but don't let that interfere with the loading of the url.  }  BrowserLoadURL(aTriggeringEvent, postData.value);}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/3e586a8f0e72ec9235c6c720d3fadc882f948a94/browser.js/clean/browser/base/content/browser.js