Fix incorrect DCHECK

We were incorrectly asserting that the disable_pop_frame_depth field
always increased instead of that it never decreased. This meant that
we would get DCHECK failures if one caused a recursive ClassPrepare or
ClassLoad event to trigger.

Test: ./test.py --host
Bug: 146170757
Change-Id: I980a8511033fa88f3fccebb7e654336133cf33bd
4 files changed