RFR (XS): 8007028: java/util/NavigableMap/LockStep hit assert(flat != TypePtr::BOTTOM) failed: cannot alias-analyze an untyped ptr

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/8007028/webrev/

EliminateAutoBox code in C2 is broken after 7017732 changes which moved 
static field (box class cache) to Class. In hs25/jdk8 this code was 
fixed but changes were big.

The fix for hs24 is to not switch on EliminateAutoBox.
I want to keep the code if later we decide to backport the fix from hs25.

Thanks,
Vladimir