Make a couple of map checks debug only.

This cost us close to 80ms in app startup times.

The checks that a reused region was within an already
existent map has been demoted to a debug check.

A couple of other negative checks have been removed
outright because one of them was superflous and the other
wasn't guaranteed to be correct.

bug: 16828525
Change-Id: I00f76de06df0ea4ced40fdcb7825248d4b662045