Add Reference.getReferent for reference intrinsic.

Reference intrinsic was incorrectly inlining PhantomReference.get().
We get around this by adding a layer of indirection. Reference.get()
now calls getReferent() which is intrinsified and inlined.

Bug: 17429865
Change-Id: I39803506c7bd800500ca3632a6cdf1077e382bff
1 file changed