[BUG] RTE: Default skin is broken

The default skin is broken in various ways.

Releases: master
Resolves: #62787
Change-Id: Ia13af7babf09de68a27e804334f34fdef9aeb942
Reviewed-on: http://review.typo3.org/33907
Reviewed-by: Stanislas Rolland <typo3@sjbr.ca>
Tested-by: Stanislas Rolland <typo3@sjbr.ca>