swift234

Fold checking of the subexpression in "x as T" into the enclosing constraint system.

Previously, we had an artificial separation between the subexpression
"x" and the context of the expression "x as T". This breaks down when
the subexpression includes a reference to an anonymous closure
argument (e.g., $0) from a single-expression closure. By merging the
systems, we fix the crasher (<rdar://problem/15633178>) and allow
improved type inference for these expressions.



Swift SVN r11235