[TASK] Remove obsolete IE6 condition in debug exception handler

Some very lonesome IE6 check can be removed for
debugging purposes now, since IE6 support has been dropped
for a long time, and for debugging purposes especially this
use-case does not exist anymore.

Resolves: #82891
Releases: master
Change-Id: I166d5becea3b1c6a53e1a1e50dcb1731332229e6
Reviewed-on: https://review.typo3.org/54515


Reviewed-by: Riccardo De Contardi <erredeco@gmail.com>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Alexander Opitz <opitz.alexander@googlemail.com>
Tested-by: Alexander Opitz <opitz.alexander@googlemail.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>