Delete cell segments using reverse iterator (as TODO comment said).
Delete cell segments using reverse iterator (as TODO comment said).

This makes it much simpler, and less error-prone.

Change-Id: I21dbe0d2bb4a71fc2ac738a5ffb03e4d959d91a5

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