[gnome-shell/gnome-40] magnifier: Unset variable holding GSource ID

[Florian Müllner <fmuellner src gnome org>]

commit 8d7be5aa56b041caf1e5b9851ea27f44f4ad6b0d
Author: Carlos Garnacho <carlosg gnome org>
Date:   Mon Jun 28 14:17:25 2021 +0200

    magnifier: Unset variable holding GSource ID
    
    Otherwise we try to remove the no longer existing GSource
    later on.
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1902>
    (cherry picked from commit a363f1343a74ae3265c11db9220ebd6eec0e21e1)

 js/ui/magnifier.js | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/js/ui/magnifier.js b/js/ui/magnifier.js
index 75cc1f9013..c4d270823b 100644
--- a/js/ui/magnifier.js
+++ b/js/ui/magnifier.js
@@ -1166,6 +1166,8 @@ var ZoomRegion = class ZoomRegion {
                 this._yDelayed = null;
             }
 
+            this._scrollContentsTimerId = 0;
+
             return GLib.SOURCE_REMOVE;
         });