[BUGFIX] RTE not resizable in IE

Incorrect test of support for CSS3 resize property.

Releases: master
Resolves: #64660
Change-Id: Id137f476920dcbf05fa028940039fa3191d808f4
Reviewed-on: http://review.typo3.org/36464


Reviewed-by: Stanislas Rolland <typo3@sjbr.ca>
Tested-by: Stanislas Rolland <typo3@sjbr.ca>