Fix tests for VM in checked mode.

pkg/serialization/lib/src/mirrors_helpers.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.
 
 /**
  * Provides some additional convenience methods on top of the basic mirrors
  */
 library mirrors_helpers;
 
 // Import and re-export mirrors here to minimize both dependence on mirrors
 // and the number of times we have to be told that mirrors aren't finished yet.
 import 'dart:mirrors';
 export 'dart:mirrors';
 import 'serialization_helpers.dart';
 
 /**
  * Return a list of all the public fields of a class, including inherited
  * fields.
  */
 List<VariableMirror> publicFields(ClassMirror mirror) {
   var mine = mirror.variables.values.where(
-      (x) => !(x.isPrivate || x.isStatic));
+      (x) => !(x.isPrivate || x.isStatic)).toList();
   var mySuperclass = mirror.superclass;
   if (mySuperclass != mirror) {
     return append(publicFields(mirror.superclass), mine);
   } else {
     return mine;
   }
 }
 
 /** Return true if the class has a field named [name]. Note that this
  * includes private fields, but excludes statics. */
@@ skipping 37 matching lines @@
   return publicGetters(mirror).where((each) =>
     setters["${each.simpleName}="] != null).toList();
 }
 
 /**
  * A particularly bad case of polyfill, because we cannot yet use type names
  * as literals, so we have to be passed an instance and then extract a
  * ClassMirror from that. Given a horrible name as an extra reminder to fix it.
  */
 ClassMirror turnInstanceIntoSomethingWeCanUse(x) => reflect(x).type;