Migrate test block 47 and downstream dependencies to Dart 2.0.

tests/language/class_cycle_test.dart

-// 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.
-
-import "package:expect/expect.dart";
-
-class Foo implements Bar {}
-
-class C {}
-
-class Bar
-    extends Foo // //# 00: compile-time error
-    implements Foo // //# 01: compile-time error
-{}
-
-class ImplementsC implements C
-, C // //# 02: compile-time error
-{}
-
-// Spec says: It is a compile-time error if the superclass
-// of a class C appears in the implements clause of C.
-class ExtendsC extends C
-implements C // //# 03: compile-time error
-{}
-
-main() {
-  Expect.isTrue(new Foo() is Foo);
-  Expect.isTrue(new ImplementsC() is C);
-  Expect.isTrue(new ExtendsC() is C);
-}