Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/global/activate/doesnt_snapshot_path_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("doesn't snapshots the executables for a path package", () {
-    d.dir(
-        'foo',
-        [
-            d.libPubspec("foo", "1.0.0"),
-            d.dir(
-                "bin",
-                [d.file("hello.dart", "void main() => print('hello!');")])]).create();
-
-    schedulePub(
-        args: ["global", "activate", "-spath", "../foo"],
-        output: isNot(contains('Precompiled foo:hello.')));
-
-    d.dir(
-        cachePath,
-        [
-            d.dir(
-                'global_packages',
-                [
-                    d.dir(
-                        'foo',
-                        [
-                            d.matcherFile('pubspec.lock', contains('1.0.0')),
-                            d.nothing('bin')])])]).validate();
-  });
-}