[BUGFIX] RTE: Missing hide method in StatusBar

Releases: master
Resolves: #63963
Change-Id: Ia7d4a77837e6c840f6118da24e444c55b395319a
Reviewed-on: http://review.typo3.org/35546
Reviewed-by: Stanislas Rolland <typo3@sjbr.ca>
Tested-by: Stanislas Rolland <typo3@sjbr.ca>