cleanup: Use type-safe comparisons

We have been using type-safe comparisons in new code for quite a while
now, however old code has only been adapted slowly.

Change all the remaining bits to get rid of another legacy style
difference.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2866>

js/gdm/batch.js

@@ -94,7 +94,7 @@ export class Hold extends Task {
     release() {
         this._acquisitions--;
 
-        if (this._acquisitions == 0)
+        if (this._acquisitions === 0)
             this.emit('release');
     }