Fix code to not hit bug in dart2js.

tests/lib/async/stream_event_transform_test.dart

 // Copyright (c) 2011, 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 stream_event_transform_test;
+
 import 'dart:async';
 import '../../../pkg/unittest/lib/unittest.dart';
 import 'event_helper.dart';
 
 void handleData(int data, StreamSink<int> sink) {
   sink.signalError(new AsyncError("$data"));
   sink.add(data + 1);
 }
+
 void handleError(AsyncError e, StreamSink<int> sink) {
   String value = e.error;
   int data = int.parse(value);
   sink.add(data);
   sink.signalError(new AsyncError("${data + 1}"));
 }
 
 void handleDone(StreamSink<int> sink) {
   sink.add(99);
   sink.close();
@@ skipping 45 matching lines @@
             handleData: handleData,
             handleError: handleError,
             handleDone: handleDone
         )));
     actual.onDone(() {
       Expect.listEquals(expected.events, actual.events);
     });
     input.replay(c);
   }
 }