ConformanceLookup: filter ReferenceStorageTypes

The remaining place where this appears to come up is while building a
substitution map, so just filter the SIL type wrappers off just before
doing lookup in the module, instead of during every lookup.

Author: kavon

lib/AST/TypeSubstitution.cpp

@@ -211,6 +211,10 @@ operator()(CanType dependentType, Type conformingReplacementType,
   if (conformingReplacementType->isTypeParameter())
     return ProtocolConformanceRef(conformedProtocol);
 
+  // Look through SIL-specific type wrappings.
+  conformingReplacementType =
+      conformingReplacementType->getReferenceStorageReferent();
+
   assert(M && "null module in conformance lookup");
   return M->lookupConformance(conformingReplacementType,
                               conformedProtocol,