VM: [Kernel] Add toString() support for generated enum classes

tests/language/enum_test.dart

 // Copyright (c) 2014, 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.
 
 import 'package:expect/expect.dart';
 
 enum Enum1 { _ }
 enum Enum2 { A }
 enum Enum3 { B, C }
 enum Enum4 { D, E, }
 enum Enum5 { F, G, H }
 enum _Enum6 { I, _J }
 
 main() {
   Expect.equals('Enum1._', Enum1._.toString());
   Expect.equals(0, Enum1._.index);
   Expect.listEquals([Enum1._], Enum1.values);
   Enum1.values.forEach(test1);
 
   Expect.equals('Enum2.A', Enum2.A.toString());
   Expect.equals(0, Enum2.A.index);
   Expect.listEquals([Enum2.A], Enum2.values);
-  Expect.identical(const [Enum2.A], Enum2.values);
+  Expect.isTrue(identical(const [Enum2.A], Enum2.values) ||
+                identical(const <Enum2>[Enum2.A], Enum2.values));

[kustermann, 2017/01/11 12:25:06]

I think dartk does the right thing by making the const list be a `const
<Enum2>[]` instead of a `const <dynamic>[]`. So I modified the test.

[Vyacheslav Egorov (Google), 2017/01/11 17:28:28]

I think it should be only one or another. 

Per specification E.values has type List<E> so the test was wrong.

We might want to file bugs against VM and dart2js about it.

[Lasse Reichstein Nielsen, 2017/01/11 17:55:00]

Agree, the spec is clear. Do file bugs (or say so, and I'll do it).

[Vyacheslav Egorov (Google), 2017/01/11 17:56:29]

It would be nice if you do that :) Thanks a (metric) ton!

   Enum2.values.forEach(test2);
 
   Expect.equals('Enum3.B', Enum3.B.toString());
   Expect.equals('Enum3.C', Enum3.C.toString());
   Expect.equals(0, Enum3.B.index);
   Expect.equals(1, Enum3.C.index);
   Expect.listEquals([Enum3.B, Enum3.C], Enum3.values);
   Enum3.values.forEach(test3);
 
   Expect.equals('Enum4.D', Enum4.D.toString());
@@ skipping 70 matching lines @@
       break;
     case Enum5.F:
       index = 0;
       break;
     case Enum5.G:
       index = 1;
       break;
   }
   Expect.equals(e.index, index);
 }