Revert "Use native async/await support in pub."

sdk/lib/_internal/pub_generated/test/oauth2/with_a_pre_existing_credentials_does_not_authenticate_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.
 
 import 'package:scheduled_test/scheduled_test.dart';
 import 'package:scheduled_test/scheduled_server.dart';
 import 'package:shelf/shelf.dart' as shelf;
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 
 main() {
   initConfig();
   integration('with a pre-existing credentials.json does not authenticate', () {
     d.validPackage.create();
 
     var server = new ScheduledServer();
     d.credentialsFile(server, 'access token').create();
     var pub = startPublish(server);
     confirmPublish(pub);
 
     server.handle('GET', '/api/packages/versions/new', (request) {
-      expect(request.headers,
+      expect(
+          request.headers,
           containsPair('authorization', 'Bearer access token'));
 
       return new shelf.Response(200);
     });
 
     pub.kill();
   });
-}
+}