Add library tags so that the tests work in dartium.

tests/isolate/global_error_handler2_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;
+
 import 'dart:async';
 import 'dart:isolate';
 
 runTest() {
   SendPort mainIsolate;
   bool isFirst = true;
   port.receive((msg, replyTo) {
     if (isFirst) {
       mainIsolate = msg;
       isFirst = false;
@@ skipping 15 matching lines @@
   var port = new ReceivePort();
   SendPort otherIsolate = spawnFunction(runTest, globalErrorHandler);
   otherIsolate.send(port.toSendPort());
   otherIsolate.send("message 2");
   port.receive((msg, replyPort) {
     Expect.equals("received", msg);
     port.close();
     timer.cancel();
   });
 }