closeDialog: Make dialog inactive while fading out

Otherwise the user might click Kill, which would crash if the fade-out
was triggered because a Wayland window was closed.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/1032

js/ui/closeDialog.js

@@ -192,6 +192,7 @@ var CloseDialog = GObject.registerClass({
         this._dialog = null;
         this._removeWindowEffect();
 
+        dialog.makeInactive();
         dialog._dialog.ease({
             scale_y: 0,
             mode: Clutter.AnimationMode.LINEAR,