in ScNavigatorDlg::ScNavigatorDlg, we replace the assignment of nAreaId
with an assignment to nDataId instead, which is never initialized but
used, whereas nAreaId was initialized but never used.

Change-Id: I9681af7f7d515d4891c9b52d3809e88e3d5e8256
Reviewed-on: https://gerrit.libreoffice.org/39062Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>