swift234

Improve type inference for the element pattern and sequence of a for-each loop.

This change pulls the handling of the element pattern and sequence of
a for-each loop into a single constraint system, so that we get type
inference between the two. Among other things, this allows one to
infer generic arguments within the element pattern from the sequence's
element type as well as allowing type annotations or the form of the
element pattern to affect overload resolution and generic argument
deduction for the sequence itself.


Swift SVN r19721