[BUGFIX] Improve marker wrapping

Inside IF structures, all markers are wrapped with single quotes.
This is not desirable for markers which we know to return
numerical values as it prevents performing mathematical
operations on them.

Resolves: #63123
Releases: 1.8
Change-Id: I93a2a391f7bc80915fd246f8349d2fa9a5458807
Reviewed-on: http://review.typo3.org/34431
Reviewed-by: Francois Suter <francois@typo3.org>
Tested-by: Francois Suter <francois@typo3.org>