sw: assert other postcondition of SwXText::Impl::ConvertCell()
sw: assert other postcondition of SwXText::Impl::ConvertCell()

Change-Id: I4fe55ac856839c04d469fa5e9b3c0fb4191e4b19

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core