Migrating a block of dart 1 tests to dart 2

tests/language/closure_in_initializer_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.
-
-// Test that a parameter used in two different closures defined in a
-// constructor initializer, is properly boxed.
-
-import "package:expect/expect.dart";
-
-class A {
-  var f;
-  var g;
-  A(a)
-      : f = (() => 42 + a),
-        g = (() => ++a) {
-    a = 4;
-  }
-}
-
-class B extends A {
-  B() : super(42);
-}
-
-class C extends A {
-  var h;
-  C(a)
-      : super(42),
-        h = (() => ++a);
-}
-
-main() {
-  var a = new A(1);
-  Expect.equals(46, a.f());
-  Expect.equals(5, a.g());
-  Expect.equals(47, a.f());
-
-  a = new B();
-  Expect.equals(46, a.f());
-  Expect.equals(5, a.g());
-  Expect.equals(47, a.f());
-
-  a = new C(0);
-  Expect.equals(46, a.f());
-  Expect.equals(5, a.g());
-  Expect.equals(47, a.f());
-  Expect.equals(1, a.h());
-  Expect.equals(2, a.h());
-  Expect.equals(47, a.f());
-  Expect.equals(6, a.g());
-  Expect.equals(48, a.f());
-}