[gnome-shell] switcherPopup: Avoid unnecessary animation

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 12ec5d1cbec367835f356b84c79ea9131deecdb4
Author: Florian Müllner <fmuellner gnome org>
Date:   Sat Jul 21 05:20:35 2018 +0200

    switcherPopup: Avoid unnecessary animation
    
    Ever since commit 28bb0c1fb2, the popup's actual visibility has been
    controlled by its :opacity property, not :visible.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/654

 js/ui/switcherPopup.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/js/ui/switcherPopup.js b/js/ui/switcherPopup.js
index 9b8cdd617..ec5bbaae9 100644
--- a/js/ui/switcherPopup.js
+++ b/js/ui/switcherPopup.js
@@ -283,7 +283,7 @@ var SwitcherPopup = GObject.registerClass({
 
     fadeAndDestroy() {
         this._popModal();
-        if (this.visible) {
+        if (this.opacity > 0) {
             Tweener.addTween(this,
                              { opacity: 0,
                                time: POPUP_FADE_OUT_TIME / 1000,