Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/dart2js/reports_dart_parse_errors_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:path/path.dart' as p;
-import 'package:scheduled_test/scheduled_test.dart';
-import 'package:scheduled_test/scheduled_stream.dart';
-
-import '../../lib/src/exit_codes.dart' as exit_codes;
-import '../descriptor.dart' as d;
-import '../test_pub.dart';
-
-main() {
-  initConfig();
-  integration("reports Dart parse errors", () {
-    // Dart2js can take a long time to compile dart code, so we increase the
-    // timeout to cope with that.
-    currentSchedule.timeout *= 3;
-
-    d.dir(
-        appPath,
-        [
-            d.appPubspec(),
-            d.dir(
-                'web',
-                [
-                    d.file('file.txt', 'contents'),
-                    d.file('file.dart', 'void void;'),
-                    d.dir('subdir', [d.file('subfile.dart', 'void void;')])])]).create();
-
-    var pub = startPub(args: ["build"]);
-    pub.stdout.expect(startsWith("Loading source assets..."));
-    pub.stdout.expect(startsWith("Building myapp..."));
-
-    var consumeFile = consumeThrough(
-        inOrder(
-            ["[Error from Dart2JS]:", startsWith(p.join("web", "file.dart") + ":")]));
-    var consumeSubfile = consumeThrough(
-        inOrder(
-            [
-                "[Error from Dart2JS]:",
-                startsWith(p.join("web", "subdir", "subfile.dart") + ":")]));
-
-    // It's nondeterministic what order the dart2js transformers start running,
-    // so we allow the error messages to be emitted in either order.
-    pub.stderr.expect(
-        either(
-            inOrder([consumeFile, consumeSubfile]),
-            inOrder([consumeSubfile, consumeFile])));
-
-    pub.shouldExit(exit_codes.DATA);
-
-    // Doesn't output anything if an error occurred.
-    d.dir(appPath, [d.dir('build', [d.nothing('web')])]).validate();
-  });
-}