ART: Cannot assume String.<init> called on NewInstance

Irreducible loops create uneliminatable phis for all live vregs. This
breaks the StringFactory optimization which assumes that the first
input is always a NewInstance instruction.

Bug: 26676472

Change-Id: Ib7dfdadbafbbfef89e1f5b1a80eb75ecf792621a
4 files changed