Pass in the context generic parameters that correspond to the substitution vector in Substitution::subst. When we build the type substitution map, also collect the conformances from the substitutions into a map we can use to fill in those conformances in substituted substitutions where necessary, without relying on the '.Archetype' field.
Swift SVN r14964
Substitute a...um...substitution by remapping its Replacement mapping and recursively remapping any ProtocolConformances it has. Modify the Specializer to use Substitution::subst when specializing the substitutions of ArchetypeMethod and Apply instructions.
Swift SVN r12900
Previously, we only tracked the mapping from associated types to their
type witnesses. Now, also track the protocol conformances for each of
the requirements placed on the associated types.
Swift SVN r6655
