Add Fasta tests.

pkg/fasta/test/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());
+}