Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/global/run/recompiles_if_sdk_is_out_of_date_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_stream.dart';
-import 'package:scheduled_test/scheduled_test.dart';
-
-import '../../descriptor.dart' as d;
-import '../../test_pub.dart';
-
-main() {
-  initConfig();
-  integration('recompiles a script if the SDK version is out-of-date', () {
-    servePackages((builder) {
-      builder.serve(
-          "foo",
-          "1.0.0",
-          contents: [
-              d.dir("bin", [d.file("script.dart", "main(args) => print('ok');")])]);
-    });
-
-    schedulePub(args: ["global", "activate", "foo"]);
-
-    d.dir(
-        cachePath,
-        [
-            d.dir(
-                'global_packages',
-                [
-                    d.dir(
-                        'foo',
-                        [d.dir('bin', [d.outOfDateSnapshot('script.dart.snapshot')])])])]).create();
-
-    var pub = pubRun(global: true, args: ["foo:script"]);
-    // In the real world this would just print "hello!", but since we collect
-    // all output we see the precompilation messages as well.
-    pub.stdout.expect("Precompiling executables...");
-    pub.stdout.expect(consumeThrough("ok"));
-    pub.shouldExit();
-
-    d.dir(
-        cachePath,
-        [
-            d.dir(
-                'global_packages',
-                [
-                    d.dir(
-                        'foo',
-                        [
-                            d.dir(
-                                'bin',
-                                [d.matcherFile('script.dart.snapshot', contains('ok'))])])])]).validate();
-  });
-}