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/animation.js

@@ -34,6 +34,7 @@ const Animation = new Lang.Class({
                 this._showFrame(0);
 
             this._timeoutId = Mainloop.timeout_add(this._speed, Lang.bind(this, this._update));
+            GLib.Source.set_name_by_id(this._timeoutId, '[gnome-shell] this._update');
         }
 
         this._isPlaying = true;