swift234

AST: Accept dependent member base type substitutions that produce archetypes.

For instance: 

protocol Fooable {
  typealias Foo
}

protocol Barrable {
  typealias Bar: Fooable

  func bar(Bar) -> Bar.Foo
}

struct FooBar<T: Fooable>: Barrable {
  typealias Bar = T

  func bar(x: T) -> T.Foo { }
}

Substituting 'T' into 'FooBar<$T>.Bar.Foo' gives 'T.Foo'. Fixes <rdar://problem/16257259>.

Swift SVN r14828