Let the open/close icons for the tree root elements reappear.

Releases: master
Resolves: #68649
Change-Id: I0a7c9065b5773a8266a7df6587887dfcd59aa416
Reviewed-on: http://review.typo3.org/42210


Reviewed-by: Benjamin Kott <info@bk2k.info>
Tested-by: Benjamin Kott <info@bk2k.info>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>