xmloff: convert legacy asserts in MultiPropertySetHelper
xmloff: convert legacy asserts in MultiPropertySetHelper

Change-Id: Ie4fb04d1c8d29eb5c7d9da4076c793a69954ab29

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