[BUGFIX] IE switching tabs with RTE ensure selectable fields

Currently if one uses IE (at least IE11) and there are two tabs
then switching from the first to second and back would result
in the fields being unselectable / unchangeable.
Setting the width of the hidden tab content to 0 ensures they are usable.

Change-Id: Ie2792ab85b7dc868d765567f02e6068722b149e1
Resolves: #70062
Releases: master
Reviewed-on: http://review.typo3.org/43529


Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Tested-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>