Remove call to deprecated ParserOptions::getMath

Since math has been moved from core to an extension
it should take care of the caching by its own.
Therefore, a call to the parserOptions::getMath is removed
and own caching logic is introduced, once getMath is removed
from core.

Bug: 14202
Change-Id: Ifa847b61264f8d640c9886fd374eb3d6cf482c0c