js: Name all the timeouts and idles

With very uninventive names. Names now, good names later.

https://bugzilla.gnome.org/show_bug.cgi?id=727983

js/ui/appDisplay.js

@@ -1402,6 +1402,7 @@ const AppIcon = new Lang.Class({
                     this.popupMenu();
                     return GLib.SOURCE_REMOVE;
                 }));
+            GLib.Source.set_name_by_id(this._menuTimeoutId, '[gnome-shell] this.popupMenu');
         } else if (button == 3) {
             this.popupMenu();
             return Clutter.EVENT_STOP;