Previously, the type of a conditional expression could be omitted if
one of the arms was just a null literal. This was meant to simplify
translation into kernel, but wasn't really worth it in terms of
complexity, and it does not work well for types that carry nullability
information.
BUG=
R=ahe@google.com
Review URL: https://codereview.chromium.org/2465263002 .
Asger Feldthaus