fastparser: avoid boost::optional where it is un-necessary.
fastparser: avoid boost::optional where it is un-necessary.

boost::optional appears to show up rather heavily on many profiles.
We already use mnElementToken == DONTKNOW to flag / use these guys.

Change-Id: Ibf2b0167f259cc601da2fb9703e880b78e60886e

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