swift234

SIL: Reorient function type lowering toward interface types.

Lower types for SILDeclRefs from the interface types of their referents, dragging the old type along for the ride so we can still offer the context to clients that haven't been weaned off of it. Make SILFunctionType's interface types and generic signature independent arguments of its  Derive the context types of SILFunctionType from the interface types, instead of the other way around. Do a bunch of annoying inseparable work in the AST and IRGen to accommodate the switchover.

Swift SVN r12536