Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/snapshot/doesnt_snapshot_path_dependency_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.
-
-library pub_tests;
-
-import 'package:path/path.dart' as p;
-import 'package:scheduled_test/scheduled_test.dart';
-
-import '../descriptor.dart' as d;
-import '../test_pub.dart';
-
-main() {
-  initConfig();
-  integration("doesn't create a snapshot for a path dependency", () {
-    d.dir(
-        "foo",
-        [
-            d.libPubspec("foo", "1.2.3"),
-            d.dir(
-                "bin",
-                [
-                    d.dir(
-                        "bin",
-                        [d.file("hello.dart", "void main() => print('hello!');")])])]).create();
-
-    d.appDir({
-      "foo": {
-        "path": "../foo"
-      }
-    }).create();
-
-    pubGet();
-
-    d.nothing(p.join(appPath, '.pub', 'bin')).validate();
-  });
-}