VM: Always return immutable collections from the mirrors.

tests/lib/mirrors/immutable_collections_test.dart

 // Copyright (c) 2013, 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.
 
 library test.immutable_collections;
 
 import 'dart:mirrors';
 import 'package:expect/expect.dart';
 
 someException(e) => e is Exception || e is Error;
@@ skipping 42 matching lines @@
   checkList(cm.typeVariables, 'ClassMirror.typeVariables');
 
   cm.methods.values.forEach(checkMethod);
   cm.getters.values.forEach(checkMethod);
   cm.setters.values.forEach(checkMethod);
   cm.constructors.values.forEach(checkMethod);
   cm.variables.values.forEach(checkVariable);
   cm.typeVariables.forEach(checkTypeVariable);
 }
 
+checkType(TypeMirror tm) {
+  checkList(tm.metadata, 'TypeMirror.metadata');
+}
+
 checkLibrary(LibraryMirror lm) {
   checkMap(lm.members, 'LibraryMirror.members');
   checkMap(lm.variables, 'LibraryMirror.variables');
   checkMap(lm.classes, 'LibraryMirror.classes');
-  // TODO(rmacnak): Revisit after members hoisted to TypeMirror.
-  // checkMap(lm.types, 'LibraryMirror.types');
+  checkMap(lm.types, 'LibraryMirror.types');
   checkMap(lm.functions, 'LibraryMirror.functions');
   checkMap(lm.getters, 'LibraryMirror.getters');
   checkMap(lm.setters, 'LibraryMirror.setters');
   checkList(lm.metadata, 'LibraryMirror.metadata');
 
-  // lm.types.forEach(checkType);
+  lm.types.values.forEach(checkType);
   lm.classes.values.forEach(checkClass);
   lm.functions.values.forEach(checkMethod);
   lm.getters.values.forEach(checkMethod);
   lm.setters.values.forEach(checkMethod);
   lm.variables.values.forEach(checkVariable);
 }
 
 main() {
   currentMirrorSystem().libraries.values.forEach(checkLibrary);
-  // checkType(currentMirrorSystem().voidType);
-  // checkType(currentMirrorSystem().dynamicType);
+  checkType(currentMirrorSystem().voidType);
+  checkType(currentMirrorSystem().dynamicType);
 }