Migrating a block of dart 1 tests to dart 2

tests/language_2/closure8_test.dart

 // Copyright (c) 2011, 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.
 // Regression test for issue 6353.
 
 class A<E> {}
 
 class C<E> extends A<E> {
   forEach(callback(E element)) {}
 }
 
 class D<E> {
   lala(E element) {}
 }
 
 main() {
   var c = new C<int>();
   c.forEach(new D<int>().lala);
 }