[BUGFIX] Display bug in FF and Opera

With the most recent versions of Firefox and Opera, the display
rules changed so that the option items of the filter menus
appear with the same color as the menu itself, makign them
unreadable. A quick fix is applied to force them to black.

Resolves: #63151
Releases: 2.11
Change-Id: Ib6adb9dcc3c3137e5e31f75a7ca8861db1f753d4
Reviewed-on: http://review.typo3.org/34644
Reviewed-by: Francois Suter <francois@typo3.org>
Tested-by: Francois Suter <francois@typo3.org>