[gnome-shell] signalTracker: Use WeakMap in SignalManager to avoid leaking objects

[Marge Bot <marge-bot src gnome org>]

commit 085102be74f4c98094712a165e5128feaca50438
Author: Sebastian Keller <skeller gnome org>
Date:   Mon Aug 29 00:03:50 2022 +0200

    signalTracker: Use WeakMap in SignalManager to avoid leaking objects
    
    The object the SignalTracker belongs to is stored in a map managed by
    the SignalManager which keeps a reference to that object. This map is
    never destroyed nor is any entry ever removed. This leads to all objects
    that ever had SignalTrackers used on them being kept alive even after
    all references outside of the SignalTracker are long gone. This then
    also extends to other objects which are leaked indirectly through
    reference chains from these objects.
    
    And if some of those objects are GObjects, this will prevent them from
    being finalized, leaking further resources. A StWidget for example will
    not release its shadow textures.
    
    Fix this by using a WeakMap in SignalManager.
    
    Closes: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/5807
    Closes: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/5796
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2450>

 js/misc/signalTracker.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/js/misc/signalTracker.js b/js/misc/signalTracker.js
index 1c3f4f9df4..8444564df4 100644
--- a/js/misc/signalTracker.js
+++ b/js/misc/signalTracker.js
@@ -42,7 +42,7 @@ class SignalManager {
     }
 
     constructor() {
-        this._signalTrackers = new Map();
+        this._signalTrackers = new WeakMap();
     }
 
     /**