Correct the position & size by roundtrip conversion
from/to wmf as a temporary solution.

Simplify a bit.

Change-Id: I59f32bd29750f9ac759800893583308f29b8aad5
Reviewed-on: https://gerrit.libreoffice.org/71860
Tested-by: Jenkins
Reviewed-by: Muhammet Kara <muhammet.kara@collabora.com>