Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/build/includes_assets_from_dependencies_test.dart

-// Copyright (c) 2013, 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("includes assets from the 'lib' directory of dependencies", () {
-    // Dart2js can take a long time to compile dart code, so we increase the
-    // timeout to cope with that.
-    currentSchedule.timeout *= 3;
-
-    d.dir(
-        "foo",
-        [
-            d.libPubspec("foo", "0.0.1"),
-            d.dir(
-                "lib",
-                [
-                    d.file("foo.txt", "foo"),
-                    d.dir("sub", [d.file("bar.txt", "bar"),])])]).create();
-
-    d.dir(appPath, [d.appPubspec({
-        "foo": {
-          "path": "../foo"
-        }
-      }),
-          d.dir("example", [d.file("index.html", "html"),]),
-          d.dir(
-              "web",
-              [
-                  d.file("index.html", "html"),
-                  d.dir("sub", [d.file("index.html", "html")])])]).create();
-
-    schedulePub(
-        args: ["build", "--all"],
-        output: new RegExp(r'Built 7 files to "build".'));
-
-    d.dir(
-        appPath,
-        [
-            d.dir(
-                'build',
-                [
-                    d.dir(
-                        'example',
-                        [
-                            d.file("index.html", "html"),
-                            d.dir(
-                                'packages',
-                                [
-                                    d.dir(
-                                        'foo',
-                                        [d.file('foo.txt', 'foo'), d.dir('sub', [d.file('bar.txt', 'bar'),]),])])]),
-                    d.dir(
-                        'web',
-                        [
-                            d.file("index.html", "html"),
-                            d.dir(
-                                'packages',
-                                [
-                                    d.dir(
-                                        'foo',
-                                        [d.file('foo.txt', 'foo'), d.dir('sub', [d.file('bar.txt', 'bar'),]),])]),
-                            d.dir(
-                                "sub",
-                                [
-                                    d.file("index.html", "html"),
-                                    // "packages" should *only* be created in the top-level directory.
-            d.nothing("packages")])])])]).validate();
-  });
-}