spinner: use a 60fps spinner

- sync with gtk+ and provide a fluid spinner

https://bugzilla.gnome.org/show_bug.cgi?id=753064

js/ui/status/network.js

@@ -877,7 +877,7 @@ const NMWirelessDialog = new Lang.Class({
                                                  y_align: Clutter.ActorAlign.CENTER });
 
         let file = Gio.File.new_for_uri('resource:///org/gnome/shell/theme/process-working.svg');
-        this._noNetworksSpinner = new Animation.AnimatedIcon(file, 24, 24);
+        this._noNetworksSpinner = new Animation.AnimatedIcon(file, 16, 16);
         this._noNetworksBox.add_actor(this._noNetworksSpinner.actor);
         this._noNetworksBox.add_actor(new St.Label({ style_class: 'no-networks-label',
                                                      text: _("No Networks") }));