(related: tdf#130685) sw: adapt definition of sw_redlinehide index 0

... to the change to use the last node - not the first node - for
paragraph properties.

The problem is that if you move the cursor around at some step of reproducing the bug, this happens:
sw/source/core/crsr/crsrsh.cxx:544: bool SwCursorShell::LRMargin(bool, bool): Assertion `sw::GetParaPropsNode(*GetLayout(), GetCursor_()->GetPoint()->nNode) == pTextNd' failed.

For a fully deleted range, it looks more plausible to map index 0 to the end of the last node instead of the start of the first node now.

This means that text will be inserted at the end of the last node too.

(regression from fa5eb82b39)

Change-Id: Ica891aea658b85211397320a44c9c10b48ca2659
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/91598
Tested-by: Jenkins
Reviewed-by: Michael Stahl <michael.stahl@cib.de>

sw/source/core/text/txtfrm.cxx

@@ -1166,7 +1166,7 @@ MapViewToModel(MergedPara const& rMerged, TextFrameIndex const i_nIndex)
     assert(nIndex == 0 && "view index out of bounds");
     return pExtent
         ? std::make_pair(pExtent->pNode, pExtent->nEnd) //1-past-the-end index
-        : std::make_pair(rMerged.pFirstNode, sal_Int32(0));
+        : std::make_pair(const_cast<SwTextNode*>(rMerged.pLastNode), rMerged.pLastNode->Len());
 }
 
 TextFrameIndex MapModelToView(MergedPara const& rMerged, SwTextNode const*const pNode, sal_Int32 const nIndex)