Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/validator/directory_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.
-
-import 'package:scheduled_test/scheduled_test.dart';
-
-import '../../lib/src/entrypoint.dart';
-import '../../lib/src/validator.dart';
-import '../../lib/src/validator/directory.dart';
-import '../descriptor.dart' as d;
-import '../test_pub.dart';
-import 'utils.dart';
-
-Validator directory(Entrypoint entrypoint) =>
-    new DirectoryValidator(entrypoint);
-
-main() {
-  initConfig();
-
-  group('should consider a package valid if it', () {
-    setUp(d.validPackage.create);
-
-    integration('looks normal', () => expectNoValidationError(directory));
-
-    integration('has a nested directory named "tools"', () {
-      d.dir(appPath, [d.dir("foo", [d.dir("tools")])]).create();
-      expectNoValidationError(directory);
-    });
-  });
-
-  group(
-      'should consider a package invalid if it has a top-level directory ' 'named',
-      () {
-    setUp(d.validPackage.create);
-
-    var names = [
-        "benchmarks",
-        "docs",
-        "examples",
-        "sample",
-        "samples",
-        "tests",
-        "tools"];
-
-    for (var name in names) {
-      integration('"$name"', () {
-        d.dir(appPath, [d.dir(name)]).create();
-        expectValidationWarning(directory);
-      });
-    }
-  });
-}