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/dnd.js

@@ -588,8 +588,9 @@ var _Draggable = class _Draggable {
                         if (this._restoreOnSuccess) {
                             this._restoreDragActor(event.get_time());
                             return true;
-                        } else
+                        } else {
                             this._dragActor.destroy();
+                        }
                     }
 
                     this._dragState = DragState.INIT;