Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/get/hosted/gets_a_package_with_busted_dev_dependencies_test.dart

-// Copyright (c) 2015, 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 pub_tests;
-
-import '../../../lib/src/exit_codes.dart' as exit_codes;
-import '../../descriptor.dart' as d;
-import '../../test_pub.dart';
-
-main() {
-  initConfig();
-
-  // Regression test for issue 22194.
-  integration(
-      'gets a dependency with broken dev dependencies from a pub ' 'server',
-      () {
-    servePackages((builder) {
-      builder.serve("foo", "1.2.3", pubspec: {
-        "dev_dependencies": {
-          "busted": {
-            "not a real source": null
-          }
-        }
-      });
-    });
-
-    d.appDir({
-      "foo": "1.2.3"
-    }).create();
-
-    pubGet();
-
-    d.cacheDir({
-      "foo": "1.2.3"
-    }).validate();
-    d.packagesDir({
-      "foo": "1.2.3"
-    }).validate();
-  });
-}