removed useless bounds checking when material_index is less than 0. This can't happen since material_index is of type usize.
removed useless bounds checking when material_index is less than 0. This can't happen since material_index is of type usize.

chrisliebert/quick-3d,chrisliebert/quick-3d,chrisliebert/quick-3d,chrisliebert/quick-3d,chrisliebert/quick-3d