Revert experimental change

browser/base/content/browser.js

@@ -933,7 +933,7 @@ function prepareForStartup()
   gBrowser.docShell.QueryInterface(Components.interfaces.nsIDocShellHistory).useGlobalHistory = true;
 
   // hook up UI through progress listener
-  //gBrowser.addProgressListener(window.XULBrowserWindow, Components.interfaces.nsIWebProgress.NOTIFY_ALL);
+  gBrowser.addProgressListener(window.XULBrowserWindow, Components.interfaces.nsIWebProgress.NOTIFY_ALL);
 
   // Initialize the feedhandler
   FeedHandler.init();