Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/upgrade/report/does_not_show_newer_versions_for_locked_packages_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.
-
-library pub_tests;
-
-import '../../descriptor.dart' as d;
-import '../../test_pub.dart';
-
-main() {
-  initConfig();
-  integration(
-      "does not show how many newer versions are available for "
-          "packages that are locked and not being upgraded",
-      () {
-    servePackages((builder) {
-      builder.serve("not_upgraded", "1.0.0");
-      builder.serve("not_upgraded", "2.0.0");
-      builder.serve("not_upgraded", "3.0.0-dev");
-      builder.serve("upgraded", "1.0.0");
-      builder.serve("upgraded", "2.0.0");
-      builder.serve("upgraded", "3.0.0-dev");
-    });
-
-    // Constraint everything to the first version.
-    d.appDir({
-      "not_upgraded": "1.0.0",
-      "upgraded": "1.0.0"
-    }).create();
-
-    pubGet();
-
-    // Loosen the constraints.
-    d.appDir({
-      "not_upgraded": "any",
-      "upgraded": "any"
-    }).create();
-
-    // Only upgrade "upgraded".
-    pubUpgrade(args: ["upgraded"], output: new RegExp(r"""
-Resolving dependencies\.\.\..*
-  not_upgraded 1\.0\.0
-. upgraded 2\.0\.0 \(was 1\.0\.0\) \(3\.0\.0-dev available\)
-""", multiLine: true));
-  });
-}