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

sdk/lib/_internal/pub_generated/test/get/path/empty_pubspec_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS d.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 d.file.
 
 import 'package:path/path.dart' as p;
 
 import '../../../lib/src/exit_codes.dart' as exit_codes;
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 
 main() {
   initConfig();
   // Regression test for issue 20103.
   integration('path dependency to an empty pubspec', () {
-    d.dir('foo', [
-      d.libDir('foo'),
-      d.file('pubspec.yaml', '')
-    ]).create();
+    d.dir('foo', [d.libDir('foo'), d.file('pubspec.yaml', '')]).create();
 
-    d.dir(appPath, [
-      d.appPubspec({
-        "foo": {"path": "../foo"}
-      })
-    ]).create();
+    d.dir(appPath, [d.appPubspec({
+        "foo": {
+          "path": "../foo"
+        }
+      })]).create();
 
-    pubGet(exitCode: exit_codes.DATA, error:
-        'Error on line 1, column 1 of ${p.join('..', 'foo', 'pubspec.yaml')}: '
+    pubGet(
+        exitCode: exit_codes.DATA,
+        error: 'Error on line 1, column 1 of ${p.join('..', 'foo', 'pubspec.yaml')}: '
             'Missing the required "name" field.');
   });
-}
+}