Handle Reference-type object in Field_get()

By fetching referent from Reference-type object directly (without
getReferent()) we run the risk of invoking the read-barrier (and hence
pushing an unmarked object to the mark-stack) when the GC doesn't expect
that to happen.

Bug: 174433134
Test: art/test/testrunner/testrunner.py --host
Change-Id: I5ff7598f9f945518db28b86a5f6ed25c39b73d05
1 file changed