Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/barback/subdirectories_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:path/path.dart' as p;
-import 'package:scheduled_test/scheduled_test.dart';
-
-import '../descriptor.dart' as d;
-import '../serve/utils.dart';
-import '../test_pub.dart';
-
-main() {
-  initConfig();
-
-  setUp(() {
-    d.dir(
-        appPath,
-        [
-            d.appPubspec(),
-            d.dir(
-                "web",
-                [
-                    d.dir("one", [d.dir("inner", [d.file("file.txt", "one")])]),
-                    d.dir("two", [d.dir("inner", [d.file("file.txt", "two")])]),
-                    d.dir("nope", [d.dir("inner", [d.file("file.txt", "nope")])])])]).create();
-  });
-
-  var webOne = p.join("web", "one");
-  var webTwoInner = p.join("web", "two", "inner");
-
-  integration("builds subdirectories", () {
-    schedulePub(
-        args: ["build", webOne, webTwoInner],
-        output: new RegExp(r'Built 2 files to "build".'));
-
-    d.dir(
-        appPath,
-        [
-            d.dir(
-                "build",
-                [
-                    d.dir(
-                        "web",
-                        [
-                            d.dir("one", [d.dir("inner", [d.file("file.txt", "one")])]),
-                            d.dir("two", [d.dir("inner", [d.file("file.txt", "two")])]),
-                            d.nothing("nope")])])]).validate();
-  });
-
-  integration("serves subdirectories", () {
-    pubServe(args: [webOne, webTwoInner]);
-
-    requestShouldSucceed("inner/file.txt", "one", root: webOne);
-    requestShouldSucceed("file.txt", "two", root: webTwoInner);
-    expectNotServed("web");
-    expectNotServed(p.join("web", "three"));
-
-    endPubServe();
-  });
-}