Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/barback/fails_on_disallowed_directories_test.dart

Index: sdk/lib/_internal/pub_generated/test/barback/fails_on_disallowed_directories_test.dart
diff --git a/sdk/lib/_internal/pub_generated/test/barback/fails_on_disallowed_directories_test.dart b/sdk/lib/_internal/pub_generated/test/barback/fails_on_disallowed_directories_test.dart
deleted file mode 100644
index 507ac4d976df00ffaeb2afd33dd0c8f2cf0913e0..0000000000000000000000000000000000000000
--- a/sdk/lib/_internal/pub_generated/test/barback/fails_on_disallowed_directories_test.dart
+++ /dev/null
@@ -1,26 +0,0 @@
-// Copyright (c) 2014, 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:path/path.dart' as path;
-import 'package:scheduled_test/scheduled_test.dart';
-
-import '../../lib/src/exit_codes.dart' as exit_codes;
-import '../descriptor.dart' as d;
-import '../test_pub.dart';
-import 'utils.dart';
-
-main() {
-  initConfig();
-
-  setUp(() {
-    d.appDir().create();
-  });
-
-  var libSub = path.join("lib", "sub");
-  pubBuildAndServeShouldFail(
-      "if given directories are not allowed",
-      args: [libSub, "lib"],
-      error: 'Directories "$libSub" and "lib" are not allowed.',
-      exitCode: exit_codes.USAGE);
-}