Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/real_version_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 'dart:io';
-
-import 'package:path/path.dart' as path;
-import 'package:scheduled_test/scheduled_process.dart';
-import 'package:scheduled_test/scheduled_test.dart';
-
-import '../lib/src/exit_codes.dart' as exit_codes;
-import '../lib/src/sdk.dart' as sdk;
-import 'test_pub.dart';
-
-main() {
-  initConfig();
-
-  // This test is a bit funny.
-  //
-  // Pub parses the "version" file that gets generated and shipped with the SDK.
-  // We want to make sure that the actual version file that gets created is
-  // also one pub can parse. If this test fails, it means the version file's
-  // format has changed in a way pub didn't expect.
-  //
-  // Note that this test expects to be invoked from a Dart executable that is
-  // in the built SDK's "bin" directory. Note also that this invokes pub from
-  // the built SDK directory, and not the live pub code directly in the repo.
-  integration('parse the real SDK "version" file', () {
-    // Get the path to the pub binary in the SDK.
-    var pubPath = path.join(
-        sdk.rootDirectory,
-        'bin',
-        Platform.operatingSystem == "windows" ? "pub.bat" : "pub");
-
-    var pub = new ScheduledProcess.start(pubPath, ['version']);
-    pub.stdout.expect(startsWith("Pub"));
-    pub.shouldExit(exit_codes.SUCCESS);
-  });
-}