ART: Fix a static_cast int32_t -> uint64_t bug.

HConstant::GetValueAsUint64 is used by SsaChecker to verify that
equivalent phis are created only for untyped constants. The test
would fail because a static_cast would sign extend the value of the
IntConstant.

Bug: 24561315
Change-Id: I818ce6a2080994a7c4395d084c1df7fd615a246d
5 files changed