st: Remove StIconType

GTK+ works by explicitly specifying a -symbolic suffix for all icons.
Do the same here.

https://bugzilla.gnome.org/show_bug.cgi?id=682540

js/ui/dash.js

@@ -256,10 +256,9 @@ const ShowAppsIcon = new Lang.Class({
 
     _createIcon: function(size) {
         this._iconActor = new St.Icon({ icon_name: 'view-grid-symbolic',
+                                        icon_size: size,
                                         style_class: 'show-apps-icon',
-                                        track_hover: true,
-                                        icon_type: St.IconType.SYMBOLIC,
-                                        icon_size: size });
+                                        track_hover: true });
         return this._iconActor;
     },