[CoroutineAccessors] Visit new accessors.

Every required accessors should be visited.  Results in the new
accessors appearing in vtables and wtables.

Author: nate-chandler

lib/AST/Decl.cpp

@@ -3132,13 +3132,19 @@ void AbstractStorageDecl::visitExpectedOpaqueAccessors(
   if (requiresOpaqueReadCoroutine())
     visit(AccessorKind::Read);
 
+  if (requiresOpaqueRead2Coroutine())
+    visit(AccessorKind::Read2);
+
   // All mutable storage should have a setter.
   if (requiresOpaqueSetter())
     visit(AccessorKind::Set);
 
   // Include the modify coroutine if it's required.
   if (requiresOpaqueModifyCoroutine())
     visit(AccessorKind::Modify);
+
+  if (requiresOpaqueModify2Coroutine())
+    visit(AccessorKind::Modify2);
 }
 
 void AbstractStorageDecl::visitOpaqueAccessors(