cleanup: Only omit braces for single-line blocks

Braces can be avoided when a block consists of a single statement,
but readability suffers when the statement spans more than a single
line.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/805

js/ui/messageTray.js

@@ -900,9 +900,10 @@ var Source = GObject.registerClass({
     }
 
     destroyNonResidentNotifications() {
-        for (let i = this.notifications.length - 1; i >= 0; i--)
+        for (let i = this.notifications.length - 1; i >= 0; i--) {
             if (!this.notifications[i].resident)
                 this.notifications[i].destroy();
+        }
     }
 });