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/pointerWatcher.js

@@ -107,6 +107,7 @@ const PointerWatcher = new Lang.Class({
 
         this._timeoutId = Mainloop.timeout_add(minInterval,
                                                Lang.bind(this, this._onTimeout));
+        GLib.Source.set_name_by_id(this._timeoutId, '[gnome-shell] this._onTimeout');
     },
 
     _onTimeout: function() {