Set the supertype to avoid loop.

dart/tests/language/cyclic_class_member_test.dart

 // Copyright (c) 2013, 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.
-//
-// Test the prohibited use of 'dynamic' in extending and implementing classes.
+
+// Test that class with a cyclic hierarchy doesn't cause a loop in dart2js.
 
 class A
-  extends dynamic  /// 00: compile-time error
-  implements dynamic  /// 01: compile-time error
+    extends A /// 01: compile-time error
 {
+  // When checking that foo isn't overriding an instance method in the
+  // superclass, dart2js might loop.
+  static foo() {}
 }
 
 main() {
   new A();
 }