[BUGFIX] ExtJS Flashmessages are not shown any more

Change-Id: Ieac7632e0c4851b28c05bc662fc3855334ac53a4
Resolves: #28462
Releases: 4.6
Reviewed-on: http://review.typo3.org/3719
Reviewed-by: Philipp Gampe
Tested-by: Philipp Gampe
Reviewed-by: Kay Strobach
Tested-by: Kay Strobach
Reviewed-by: Steffen Gebert
Tested-by: Steffen Gebert