sw: fix assert in SwViewShell::FillPrtDoc()
The point node isn't necessarily the start node; this will assert in
SwTextFrame::MapModelToView: Assertion `SwFrame::GetDep() == pNode' failed
when selecting a table and then File->Print->Print Selection.
Thanks Samuel for the hint.
(regression from
067a53bbcd209d7458b04142f989e1ff7ec1f785)
Change-Id: I7f58b79e068e8b7817261e81f999721ebfcfdcf1
Reviewed-on: https://gerrit.libreoffice.org/65421
Tested-by: Jenkins
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>