Move kernel baseline tests to front_end.

pkg/front_end/testcases/cycles.dart

 // Copyright (c) 2016, 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.
 
 class A implements C {
 }
 
 class B extends A {
 }
 
 class C extends B implements D {
 }
 
 class D {
 }
 
 main() {
   print(new A());
   print(new B());
   print(new C());
   print(new D());
 }