[BUGFIX] Element Browser uses non-namespaced code

Followup to #36817, where an old patch was moved to
the new namespaced code, but without refactoring the
code itself (my fault). The change fixes this.

Change-Id: I9e25a86af68dace1f605d6dfd6bf917350939f31
Releases: 6.0
Resolves: #41834
Reviewed-on: http://review.typo3.org/15482
Reviewed-by: Steffen Ritter
Tested-by: Steffen Ritter