[IRGen/TBDGen] Minor fixes for opaque result types.

Fixes rdar://problem/50001229.

Author: aschwaighofer

lib/IRGen/GenDecl.cpp

@@ -2161,8 +2161,7 @@ void IRGenModule::emitOpaqueTypeDescriptorAccessor(OpaqueTypeDecl *opaque) {
   auto accessor =
       getAddrOfOpaqueTypeDescriptorAccessFunction(opaque, ForDefinition, false);
 
-  if (cast<AbstractFunctionDecl>(opaque->getNamingDecl())
-      ->isNativeDynamic()) {
+  if (opaque->getNamingDecl()->isNativeDynamic()) {
     auto thunk = accessor;
     auto impl =
       getAddrOfOpaqueTypeDescriptorAccessFunction(opaque, ForDefinition, true);

lib/TBDGen/TBDGen.cpp

@@ -267,6 +267,7 @@ void TBDGenVisitor::visitAbstractStorageDecl(AbstractStorageDecl *ASD) {
   // ...and the opaque result decl if it has one.
   if (auto opaqueResult = ASD->getOpaqueResultTypeDecl()) {
     addSymbol(LinkEntity::forOpaqueTypeDescriptor(opaqueResult));
+    addSymbol(LinkEntity::forOpaqueTypeDescriptorAccessor(opaqueResult));
   }
 
   // Explicitly look at each accessor here: see visitAccessorDecl.