messageTray: Clean up "TODO" code

The code here says to remove it after the GNOME3 release. Better late
than never.

js/ui/messageTray.js

@@ -141,14 +141,9 @@ const URLHighlighter = new Lang.Class({
                 let url = this._urls[urlId].url;
                 if (url.indexOf(':') == -1)
                     url = 'http://' + url;
-                try {
+
                 Gio.app_info_launch_default_for_uri(url, global.create_app_launch_context());
                 return true;
-                } catch (e) {
-                    // TODO: remove this after gnome 3 release
-                    Util.spawn(['gvfs-open', url]);
-                    return true;
-                }
             }
             return false;
         }));