My previous commit has disabled setting non-text for selection, so
this workaround is no longer needed (and it very much looks like
a workaround, I see no good reason for never putting images
in the clipboard).

This reverts commit c8b0c382.

Change-Id: I0206211e3ff0adcb89f8ca5410831a428e71fb51
Reviewed-on: https://gerrit.libreoffice.org/72370
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>