Revert "Revert "Use native async/await support in pub.""

sdk/lib/_internal/pub_generated/test/upgrade/git/upgrade_to_incompatible_pubspec_test.dart

-// Copyright (c) 2012, 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:scheduled_test/scheduled_test.dart';
-
-import '../../../lib/src/exit_codes.dart' as exit_codes;
-import '../../descriptor.dart' as d;
-import '../../test_pub.dart';
-
-main() {
-  initConfig();
-  integration("upgrades Git packages to an incompatible pubspec", () {
-    ensureGit();
-
-    d.git('foo.git', [d.libDir('foo'), d.libPubspec('foo', '1.0.0')]).create();
-
-    d.appDir({
-      "foo": {
-        "git": "../foo.git"
-      }
-    }).create();
-
-    pubGet();
-
-    d.dir(
-        packagesPath,
-        [d.dir('foo', [d.file('foo.dart', 'main() => "foo";')])]).validate();
-
-    d.git('foo.git', [d.libDir('zoo'), d.libPubspec('zoo', '1.0.0')]).commit();
-
-    pubUpgrade(
-        error: contains('"name" field doesn\'t match expected name ' '"foo".'),
-        exitCode: exit_codes.DATA);
-
-    d.dir(
-        packagesPath,
-        [d.dir('foo', [d.file('foo.dart', 'main() => "foo";')])]).validate();
-  });
-}