[CLEANUP] Replace count with empty in EXT:rtehtmlarea

Replace occurences of count() with matching empty() pendants.

Resolves: #67953
Releases: master
Change-Id: I22eef6d10406f5cc1d1d85a7179f98240083f178
Reviewed-on: http://review.typo3.org/40957


Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Stephan Großberndt <stephan@grossberndt.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>