swift234

Allow references to deduced associated types.

When checking a type's conformance against a protocol, we can deduce
the values of associated types. Make these associated types visible to
qualified name lookup so that (for example) VectorEnumeratorType does
not need to define the Element type. It is deduced from the signautre
of next(), and made available as, e.g.,
VectorEnumeratorType<Int>.Element through the Enumerator protocol
conformance. Fixes <rdar://problem/11510701>, but with some lingering
dependencies on lazy type resolution (<rdar://problem/12202655>).

Note that the infrastructure here is meant to be generalized to
support default implementations in protocols, but there are several
pieces still not in place.



Swift SVN r6073