#i122752# check iterator in each iteration of CFormatEtcContainer::nextFormatEtc()'s loop
#i122752# check iterator in each iteration of CFormatEtcContainer::nextFormatEtc()'s loop

Don't trust nextFormatEtc()'s aNum argument not to mislead the iterator beyond
the container bounds. The comparable loop in CFormatEtcContainer::skipFormatEtc()
already checks the iterator against the container end in each iteration.

(cherry picked from commit a609daa146c5588c6a35c2c145e9573c625ec123)

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