A SpecializedProtocolConformance intentionally contains all of the
information we need to synthesize the type witnesses from the
underlying (generic) conformance. Do so lazily rather than eagerly,
because we won't always need all of them.
As a nice side effect, we no longer need to serialize the witnesses of
these specialized protocol conformances, so we can save some space in
the Swift module file.
Swift SVN r11303
It's useful to know what the open type variables in a generic protocol conformance are. For now, make the somewhat shaky assumptions that a NormalProtocolConformance for a bound generic type is for the DeclaredTypeInContext of its originating nominal type, that all type variables of the nominal type are open, and that specialized and inherited conformances bind all of the generic parameters.
Swift SVN r11274
