style: Fix brace style

Opening braces should be on the same line as the associated statement,
and only be omitted if both surrounding blocks are one-liners.

Partially spotted by eslint.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/607

js/ui/popupMenu.js

@@ -851,8 +851,9 @@ var PopupMenu = class extends PopupMenuBase {
                 this.toggle();
             this.actor.navigate_focus(null, St.DirectionType.TAB_FORWARD, false);
             return Clutter.EVENT_STOP;
-        } else
+        } else {
             return Clutter.EVENT_PROPAGATE;
+        }
     }
 
     setArrowOrigin(origin) {