[BUGFIX] Fix JavaScript error that prevents links to anchor tags in RTE

This patch fixes invalid JavaScript code (adds a missing closing
bracket), that prevents BE users from creating links to anchor tags
in the RTE.

This is a regression fix to #41413.

Resolves: #61943
Releases: master, 6.2
Change-Id: I8e085e01885333d612cf6776495be259b00a093a
Reviewed-on: http://review.typo3.org/33067
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>