swift234

[serialization] XRefs to types can be fully resolved by their names.

Simplify/clarify a condition that was attempting to avoid a particular
circularity: the value type of a NominalTypeDecl for type T is T.metatype.
Normally, we use the type of a value decl to verify that we actually have
the thing we want (and in the case of functions, to pick a particular
overload). In this case, however, trying to deserialize a reference to
T.metatype ends up just trying to deserialize T again -- it's not in our
lookup table because the deserializer isn't yet sure it's the /right/ T.

The existing code avoided this with a hack: check if the ValueDecl's type
is a metatype. The new code actually does the right thing and checks for
a TypeDecl.

Swift SVN r9038