Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/global/activate/git_package_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('activates a package from a Git repo', () {
-    ensureGit();
-
-    d.git(
-        'foo.git',
-        [
-            d.libPubspec("foo", "1.0.0"),
-            d.dir("bin", [d.file("foo.dart", "main() => print('ok');")])]).create();
-
-    schedulePub(
-        args: ["global", "activate", "-sgit", "../foo.git"],
-        output: allOf(
-            startsWith('Resolving dependencies...\n' '+ foo 1.0.0 from git ../foo.git at '),
-            // Specific revision number goes here.
-    endsWith(
-        'Precompiling executables...\n' 'Loading source assets...\n'
-            'Precompiled foo:foo.\n'
-            'Activated foo 1.0.0 from Git repository "../foo.git".')));
-  });
-}