Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/global/binstubs/binstub_runs_precompiled_snapshot_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("the binstubs runs a precompiled snapshot if present", () {
-    servePackages((builder) {
-      builder.serve("foo", "1.0.0", pubspec: {
-        "executables": {
-          "foo-script": "script"
-        }
-      },
-          contents: [
-              d.dir("bin", [d.file("script.dart", "main(args) => print('ok');")])]);
-    });
-
-    schedulePub(args: ["global", "activate", "foo"]);
-
-    d.dir(
-        cachePath,
-        [
-            d.dir(
-                "bin",
-                [
-                    d.matcherFile(
-                        binStubName("foo-script"),
-                        contains("script.dart.snapshot"))])]).validate();
-  });
-}