Eliminate another unnecessary use of an archetype's generic environment

Author: DougGregor

lib/Sema/CSSimplify.cpp

@@ -8808,8 +8808,8 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyMemberConstraint(
             baseTy->getMetatypeInstanceType()->getAs<ArchetypeType>()) {
       if (auto genericTy =
               archetype->mapTypeOutOfContext()->getAs<GenericTypeParamType>()) {
-        for (auto param :
-             archetype->getGenericEnvironment()->getGenericParams()) {
+        for (auto param : DC->getGenericSignatureOfContext()
+                              .getGenericParams()) {
           // Find a param at the same depth and one index past the type we're
           // dealing with
           if (param->getDepth() != genericTy->getDepth() ||