Kill stale assert, fix for 4310384

Kill stale assert, fix for 4310384

There was an old assert in dvmPopFrame that did a sanity check on
the JNI local reference table it was popping.  In the asserting case,
we had internal native method calls and no JNI - and thus no sane
local reference table.  Further, the localRefTable code has changed enough
that this particular sanity check is no longer useful.  Assert deleted,
along with another related (and previously-commented out) assert.

Change-Id: I3a806838fa2b5909c3e3b3ad27aeed29e3e467ab