Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/global/binstubs/binstub_runs_executable_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 'dart:io';
-
-import 'package:path/path.dart' as p;
-import 'package:scheduled_test/scheduled_process.dart';
-import 'package:scheduled_test/scheduled_test.dart';
-
-import '../../descriptor.dart' as d;
-import '../../test_pub.dart';
-import 'utils.dart';
-
-main() {
-  initConfig();
-  integration("the generated binstub runs a snapshotted executable", () {
-    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 \$args');")])]);
-    });
-
-    schedulePub(args: ["global", "activate", "foo"]);
-
-    var process = new ScheduledProcess.start(
-        p.join(sandboxDir, cachePath, "bin", binStubName("foo-script")),
-        ["arg1", "arg2"],
-        environment: getEnvironment());
-
-    process.stdout.expect("ok [arg1, arg2]");
-    process.shouldExit();
-  });
-
-  integration("the generated binstub runs a non-snapshotted executable", () {
-    d.dir("foo", [d.pubspec({
-        "name": "foo",
-        "executables": {
-          "foo-script": "script"
-        }
-      }),
-          d.dir(
-              "bin",
-              [d.file("script.dart", "main(args) => print('ok \$args');")])]).create();
-
-    schedulePub(args: ["global", "activate", "-spath", "../foo"]);
-
-    var process = new ScheduledProcess.start(
-        p.join(sandboxDir, cachePath, "bin", binStubName("foo-script")),
-        ["arg1", "arg2"],
-        environment: getEnvironment());
-
-    process.stdout.expect("ok [arg1, arg2]");
-    process.shouldExit();
-  });
-}