tdf#83223: sw: fix Undo of format change of conditional para style

SwUndoFormatAttr was simply missing a case for RES_CONDTXTFMTCOLL.
Handle it the same way as an oridnary paragraph style, which seems to
work for me.

Change-Id: Ib529beb1116633e4890d5b51df39da21de485db9
(cherry picked from commit 37e93699)
Reviewed-on: https://gerrit.libreoffice.org/17428Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>

sw/source/core/undo/unattr.cxx

@@ -204,6 +204,7 @@ bool SwUndoFormatAttr::IsFormatInDoc( SwDoc* pDoc )
     switch ( m_nFormatWhich )
     {
         case RES_TXTFMTCOLL:
+        case RES_CONDTXTFMTCOLL:
             bFound = pDoc->GetTextFormatColls()->Contains( m_pFormat );
             break;
 
@@ -301,7 +302,9 @@ void SwUndoFormatAttr::RepeatImpl(::sw::RepeatContext & rContext)
     }
     break;
 
-    case RES_TXTFMTCOLL: {
+    case RES_TXTFMTCOLL:
+    case RES_CONDTXTFMTCOLL:
+    {
         SwTextNode *const pNd =
             rContext.GetRepeatPaM().GetNode().GetTextNode();
         if( pNd ) {