[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 #60919.

Resolves: #61943
Releases: master, 6.2, 6.1, 4.7, 4.5
Change-Id: I90ecba126191322048a2c4aca7835d3795764324
Reviewed-on: http://review.typo3.org/33055
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>