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

(cherry picked from commit bddaea2b)

Change-Id: Ia6f3e69692bb9cb5b4ff6f47946ea38a56d4cdb6