Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/global/activate/snapshots_hosted_executables_test.dart

-// Copyright (c) 2014, 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:scheduled_test/scheduled_test.dart';
-
-import '../../descriptor.dart' as d;
-import '../../test_pub.dart';
-
-main() {
-  initConfig();
-  integration('snapshots the executables for a hosted package', () {
-    servePackages((builder) {
-      builder.serve(
-          "foo",
-          "1.0.0",
-          contents: [
-              d.dir(
-                  'bin',
-                  [
-                      d.file("hello.dart", "void main() => print('hello!');"),
-                      d.file("goodbye.dart", "void main() => print('goodbye!');"),
-                      d.file("shell.sh", "echo shell"),
-                      d.dir("subdir", [d.file("sub.dart", "void main() => print('sub!');")])])]);
-    });
-
-    schedulePub(
-        args: ["global", "activate", "foo"],
-        output: allOf(
-            [contains('Precompiled foo:hello.'), contains("Precompiled foo:goodbye.")]));
-
-    d.dir(
-        cachePath,
-        [
-            d.dir(
-                'global_packages',
-                [
-                    d.dir(
-                        'foo',
-                        [
-                            d.matcherFile('pubspec.lock', contains('1.0.0')),
-                            d.dir(
-                                'bin',
-                                [
-                                    d.matcherFile('hello.dart.snapshot', contains('hello!')),
-                                    d.matcherFile('goodbye.dart.snapshot', contains('goodbye!')),
-                                    d.nothing('shell.sh.snapshot'),
-                                    d.nothing('subdir')])])])]).validate();
-  });
-}