Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/hosted/fail_gracefully_on_url_resolve_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.
-
-library pub_tests;
-
-import '../../lib/src/exit_codes.dart' as exit_codes;
-import '../descriptor.dart' as d;
-import '../test_pub.dart';
-
-main() {
-  initConfig();
-
-  forBothPubGetAndUpgrade((command) {
-    integration('fails gracefully if the url does not resolve', () {
-      d.dir(appPath, [d.appPubspec({
-          "foo": {
-            "hosted": {
-              "name": "foo",
-              "url": "http://pub.invalid"
-            }
-          }
-        })]).create();
-
-      pubCommand(
-          command,
-          error: 'Could not resolve URL "http://pub.invalid".',
-          exitCode: exit_codes.UNAVAILABLE);
-    });
-  });
-}