Change reflective serialization rules to be able to take type literals

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
@@ skipping 64 matching lines @@
  * Return a list of all the public getters of a class which have corresponding
  * setters.
  */
 Iterable<MethodMirror> publicGettersWithMatchingSetters(ClassMirror mirror) {
   var setters = mirror.setters;
   return publicGetters(mirror).where((each) =>
     setters["${each.simpleName}="] != null);
 }
 
 /**
- * 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.
+ * Given either an instance or a type, returns the type. Instances of Type
+ * will be treated as types. Passing in an instance is really just backward
+ * compatibility.
  */
-ClassMirror turnInstanceIntoSomethingWeCanUse(x) => reflect(x).type;
+ClassMirror turnInstanceIntoSomethingWeCanUse(x) {
+  if (x is Type) return reflectClass(x);
+  return reflect(x).type;
+}