Include super type in interface list for cycle detection (issue 4318).

tests/language/class_cycle_test.dart

Index: tests/language/class_cycle_test.dart
===================================================================
--- tests/language/class_cycle_test.dart	(revision 0)
+++ tests/language/class_cycle_test.dart	(revision 0)
@@ -0,0 +1,23 @@
+// Copyright (c) 2012, 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.
+// Check fail because of cycles in super class relationship.
+
+class Foo implements Bar {
+}
+
+class C {
+}
+
+class Bar
+    extends Foo  /// 00: compile-time error
+    implements Foo  /// 01: compile-time error
+    implements C, C  /// 02: compile-time error
+    extends C implements C  /// 03: compile-time error
+{
+}
+
+main() {
+  Expect.isTrue(new Foo() is Foo);
+}
+