swift234

Map Objective-C's 'id' to Swift's NSObject.

Objective-C's 'id' is a very odd type, because it effectively acts as
both a "top" and a "bottom" for the lattice of Objective-C types,
where "top" is a type everything is a subtype of an "bottom" is a type
everything is a supertype of. We almost surely don't want the "bottom"
behavior in Swift, but we also don't have a suitable notion of "top"
yet. protocol<> is closest, but that's too general because it also
allows value types. NSObject is the closest thing we have, for now, so
we use it.


Swift SVN r3260