Update unittest to new package layout.

tests/isolate/message_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.
 
 // Dart test program for testing serialization of messages.
 // VMOptions=--enable_type_checks --enable_asserts
 
 #library('MessageTest');
 #import("dart:isolate");
-#import('../../pkg/unittest/unittest.dart');
+#import('../../pkg/unittest/lib/unittest.dart');
 
 // ---------------------------------------------------------------------------
 // Message passing test.
 // ---------------------------------------------------------------------------
 
 class MessageTest {
   static const List list1 = const ["Hello", "World", "Hello", 0xfffffffffff];
   static const List list2 = const [null, list1, list1, list1, list1];
   static const List list3 = const [list2, 2.0, true, false, 0xfffffffffff];
   static const Map map1 = const {
@@ skipping 98 matching lines @@
       // Bigint literals are not canonicalized so do a == check.
       Expect.equals(true, replyObject[0][3] == replyObject[4][4]);
     });
 
     // Shutdown the MessageServer.
     remote.call(-1).then(expectAsync1((int message) {
         Expect.equals(MessageTest.elms.length + 1, message);
       }));
   });
 }