[BUGFIX] RTE Spellcheck dialogue not correctly displayed

The RTE Spellcheck dialogue is not correctly displayed: the suggestions
and dictionaries fieldsets are never displayed in Firefox and Chrome
due to size constraints. In IE, the trigger elements of the combo boxes
are truncated on the right.

Releases: master, 6.2
Resolves: #62114
Change-Id: Iebff324164dc5975403e2217dd06def77e2eba6f
Reviewed-on: http://review.typo3.org/33218
Reviewed-by: Stanislas Rolland <typo3@sjbr.ca>
Tested-by: Stanislas Rolland <typo3@sjbr.ca>