[gnome-shell] messageTray: Remove this.actor definition to SourceActor

[Florian Müllner <fmuellner src gnome org>]

commit bea6045aaecfe5c584e2f2a2508ec39c8ef3b4c6
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Tue Apr 9 18:25:30 2019 -0500

    messageTray: Remove this.actor definition to SourceActor
    
    Remove this.actor = actor, since the class is now an actor itself.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/487

 js/ui/messageTray.js | 1 -
 1 file changed, 1 deletion(-)
---
diff --git a/js/ui/messageTray.js b/js/ui/messageTray.js
index 8f8130451..f1f79d8c2 100644
--- a/js/ui/messageTray.js
+++ b/js/ui/messageTray.js
@@ -584,7 +584,6 @@ class SourceActor extends St.Widget {
         this._source = source;
         this._size = size;
 
-        this.actor = this;
         this.connect('destroy', () => {
             this._source.disconnect(this._iconUpdatedId);
             this._actorDestroyed = true;