Convert pkg/serialization imports to "package:".

pkg/serialization/test/serialization_test.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.
 
 library serialization_test;
 
-import '../../unittest/lib/unittest.dart';
-import '../lib/serialization.dart';
-import '../lib/src/serialization_helpers.dart';
-import '../lib/src/mirrors_helpers.dart';
+import 'package:unittest/unittest.dart';
+import 'package:serialization/serialization.dart';
+import 'package:serialization/src/serialization_helpers.dart';
+import 'package:serialization/src/mirrors_helpers.dart';
 
 part 'test_models.dart';
 
 main() {
   var p1 = new Person();
   var a1 = new Address();
   a1.street = 'N 34th';
   a1.city = 'Seattle';
 
   test('Basic extraction of a simple object', () {
@@ skipping 475 matching lines @@
 /** A hard-coded rule for serializing Node instances. */
 class NodeRule extends CustomRule {
   bool appliesTo(instance, _) => instance is Node;
   getState(instance) => [instance.parent, instance.name, instance.children];
   create(state) => new Node(state[1]);
   setState(Node node, state) {
     node.parent = state[0];
     node.children = state[2];
   }
 }