cleanup: Remove empty leading/trailing lines in blocks

gjs added a new rule to its eslint ruleset that forbids "block padding",
so make sure we conform to that rule before syncing up the configuration.

https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1498

js/ui/altTab.js

@@ -907,7 +907,6 @@ class ThumbnailSwitcher extends SwitcherPopup.SwitcherList {
             } else {
                 this.addItem(box, null);
             }
-
         }
 
         this.connect('destroy', this._onDestroy.bind(this));