Bug 624123 - Titlebar too big after leaving full screen if tab groups were used. r=gavin

--HG--
extra : rebase_source : f6021917bcd7b876865a3bcceee939ab19e03564

browser/base/content/browser.js

@@ -4875,7 +4875,7 @@ var TabsInTitlebar = {
   },
 
   _update: function () {
-    if (!this._initialized)
+    if (!this._initialized || window.fullScreen)
       return;
 
     let allowed = true;