Sequence::operator[]: let's cast the other side to unsigned too
Sequence::operator[]: let's cast the other side to unsigned too

Change-Id: I30845477e5dfbf5c90702bb0b6acb7955fcbe684

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