js/ui: Always use namespace for animation modes

Clutter.Animation doesn't contain any animation modes, they live in
Clutter.AnimationMode. The places we did `Clutter.Animation.WHATEVER`
just evaluated to `undefined`. Thus, use the correct namespace for the
animation mode enums.

https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1199

js/ui/panel.js

@@ -281,7 +281,7 @@ var AppMenuButton = GObject.registerClass({
         this.remove_all_transitions();
         this.ease({
             opacity: 0,
-            mode: Clutter.Animation.EASE_OUT_QUAD,
+            mode: Clutter.AnimationMode.EASE_OUT_QUAD,
             duration: Overview.ANIMATION_TIME,
             onComplete: () => this.hide(),
         });