fdo#60789: writerfilter: do not insert a character at field start

The character inserted in DomainMapper_Impl::PushFieldContext() causes
problems in this bugdoc because there is a commentRangeStart immediately
before a text field and the call to delete it via setString("") disposes
the SwXTextRange that is stored in m_aAnnotationPosition.m_xStart,
which results in an exception when trying to insert the comment.

At least all the fields in the bugdoc import fine with this change.

Change-Id: I6c08d72fafb0529e8612f1e35b2c8b871edb5a52

writerfilter/source/dmapper/DomainMapper_Impl.cxx

@@ -2035,10 +2035,7 @@ void DomainMapper_Impl::PushFieldContext()
     uno::Reference< text::XTextRange > xStart;
     if (xTextAppend.is())
     {
-        //insert a dummy char to make sure the start range doesn't move together with the to-be-appended text
-        xTextAppend->appendTextPortion(OUString( '-' ), uno::Sequence< beans::PropertyValue >() );
         uno::Reference< text::XTextCursor > xCrsr = xTextAppend->createTextCursorByRange( xTextAppend->getEnd() );
-        xCrsr->goLeft( 1, false );
         xStart = xCrsr->getStart();
     }
     m_aFieldStack.push( FieldContextPtr( new FieldContext( xStart ) ) );
@@ -3312,9 +3309,6 @@ void DomainMapper_Impl::PopFieldContext()
             try
             {
                 uno::Reference< text::XTextCursor > xCrsr = xTextAppend->createTextCursorByRange(pContext->GetStartRange());
-                //remove the dummy character
-                xCrsr->goRight( 1, true );
-                xCrsr->setString( OUString() );
                 uno::Reference< text::XTextContent > xToInsert( pContext->GetTOC(), uno::UNO_QUERY );
                 if( xToInsert.is() )
                 {