coverity#1209374 avoid division by 0
coverity#1209374 avoid division by 0

Change-Id: I6728c0f79e0091b88b3269f5b8b25d27c82d9761

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