[BUGFIX] Assure same WS ID for children of containers in a WS only

Change-Id: I3ada817e0b4556b5bb1b30e143ff8f41d0b86bda
Resolves: #63958
Releases: master
Reviewed-on: http://review.typo3.org/35547
Reviewed-by: Jo Hasenau <info@cybercraft.de>
Tested-by: Jo Hasenau <info@cybercraft.de>