Improve simplifier slightly

It's possible thanks to the dead-code-elimination and other passes to
end up with a PredicatedInstanceFieldGet that either has a null or a
'never-null' target value. We can simplify this down to either the
default value or a normal ifield-get respectively.

Test: ./test.py --host
Change-Id: I92d9ff159a7b30294d29dbf4349d201dc654f0e1
2 files changed