More work on finalization of recursive types (fixes #29357).

tests/language/regress_29357_test.dart

Index: tests/language/regress_29357_test.dart
diff --git a/tests/language/regress_29357_test.dart b/tests/language/regress_29357_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..3777e3cc2239a72ffe3704ead2a49304ee1c1787
--- /dev/null
+++ b/tests/language/regress_29357_test.dart
@@ -0,0 +1,18 @@
+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+abstract class A<T extends A<T>> {}
+
+abstract class B<T extends A<T>> {}
+
+class C<U> extends B<D<U>> {}
+
+class D<U> extends A<D<U>> {}
+
+main() {
+  new D();
+  new C();
+  new D<C>();
+  new C<D>();
+}