Implement ClosureMirror.

dart/tests/lib/mirrors/mirrors_test.dart

Index: dart/tests/lib/mirrors/mirrors_test.dart
diff --git a/dart/tests/lib/mirrors/mirrors_test.dart b/dart/tests/lib/mirrors/mirrors_test.dart
index 7509467f4a36513c8585bb66d8f1b415af9c3a7b..a9fd46d9019959873be7a31ff567570d945e0bf8 100644
--- a/dart/tests/lib/mirrors/mirrors_test.dart
+++ b/dart/tests/lib/mirrors/mirrors_test.dart
@@ -105,6 +105,7 @@ testFieldAccess(mirrors) {
 }
 
 testClosureMirrors(mirrors) {
+  // TODO(ahe): Test optional parameters (named or not).
   var closure = (x, y, z) { return x + y + z; };
 
   var mirror = reflect(closure);
@@ -204,8 +205,8 @@ mainWithArgument({bool isDart2js}) {
   test("Test instance field access", () { testInstanceFieldAccess(mirrors); });
   test('Test intercepted objects', () { testIntercepted(mirrors); });
   test("Test field access", () { testFieldAccess(mirrors); });
-  if (isDart2js) return;
   test("Test closure mirrors", () { testClosureMirrors(mirrors); });
+  if (isDart2js) return;
   test("Test invoke constructor", () { testInvokeConstructor(mirrors); });
   test("Test reflect type", () { testReflectClass(mirrors); });
   test("Test simple and qualifiedName", () { testNames(mirrors); });