[BUGFIX] Add overflow for content element preview in page module

Improve rendering of content elements in page module

Change-Id: Icaa3de084b2d58b43e7a3fa088542677401af246
Resolves: #70203
Releases: master
Reviewed-on: http://review.typo3.org/43650


Reviewed-by: Stefan Froemken <froemken@gmail.com>
Tested-by: Stefan Froemken <froemken@gmail.com>
Reviewed-by: Josef Glatz <jousch@gmail.com>
Tested-by: Josef Glatz <jousch@gmail.com>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>