Add support for Enums

test/codegen/expect/fieldtest.js

 dart_library.library('fieldtest', null, /* Imports */[
   "dart_runtime/dart",
   'dart/core'
 ], /* Lazy imports */[
 ], function(exports, dart, core) {
   'use strict';
   let dartx = dart.dartx;
   class A extends core.Object {
     A() {
       this.x = 42;
@@ skipping 74 matching lines @@
   class StaticFieldOrder1 extends core.Object {}
   StaticFieldOrder1.d = 4;
   StaticFieldOrder1.c = dart.notNull(StaticFieldOrder1.d) + 2;
   StaticFieldOrder1.b = dart.notNull(StaticFieldOrder1.c) + 3;
   StaticFieldOrder1.a = dart.notNull(StaticFieldOrder1.b) + 1;
   class StaticFieldOrder2 extends core.Object {}
   StaticFieldOrder2.d = 4;
   StaticFieldOrder2.c = dart.notNull(StaticFieldOrder2.d) + 2;
   StaticFieldOrder2.b = dart.notNull(StaticFieldOrder2.c) + 3;
   StaticFieldOrder2.a = dart.notNull(StaticFieldOrder2.b) + 1;
+  class MyEnum extends core.Object {
+    MyEnum(index) {
+      this.index = index;
+    }
+    toString() {
+      return {
+        0: "MyEnum.Val1",
+        1: "MyEnum.Val2",
+        2: "MyEnum.Val3",
+        3: "MyEnum.Val4"
+      }[this.index];
+    }
+  };
+  MyEnum.Val1 = dart.const(new MyEnum(0));
+  MyEnum.Val2 = dart.const(new MyEnum(1));
+  MyEnum.Val3 = dart.const(new MyEnum(2));
+  MyEnum.Val4 = dart.const(new MyEnum(3));
+  MyEnum.values = dart.const(dart.list([MyEnum.Val1, MyEnum.Val2, MyEnum.Val3, MyEnum.Val4], MyEnum));
   function main() {
     let a = new A();
     foo(a);
     bar(a);
     core.print(baz(a));
     core.print(new (Generic$(core.String))().foo(' world'));
+    core.print(MyEnum.values);
   }
   dart.fn(main, dart.void, []);
   // Exports:
   exports.A = A;
   exports.B$ = B$;
   exports.B = B;
   exports.foo = foo;
   exports.bar = bar;
   exports.baz = baz;
   exports.compute = compute;
   exports.BaseWithGetter = BaseWithGetter;
   exports.Derived = Derived;
   exports.Generic$ = Generic$;
   exports.Generic = Generic;
   exports.StaticFieldOrder1 = StaticFieldOrder1;
   exports.StaticFieldOrder2 = StaticFieldOrder2;
   exports.main = main;
 });