[!!!][BUGFIX] Assign first class for tables in HTMLparser

When the given class of a table is not valid by configuration,
the HTMLparser should assign the first class in configuration instead
of generating an empty class attribute.

Releases: master
Resolves: #24186
Change-Id: Ia57c036aaf81973e8d7fe26861c78de217013c75
Reviewed-on: http://review.typo3.org/39349


Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Susanne Moog <typo3@susannemoog.de>
Tested-by: Susanne Moog <typo3@susannemoog.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>