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

sdk/lib/_internal/pub_generated/test/serve/does_not_serve_hidden_assets_test.dart

 // Copyright (c) 2014, 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 file.
 
 library pub_tests;
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import 'utils.dart';
 
 main() {
   initConfig();
   integration("doesn't serve hidden assets", () {
-    d.dir(appPath, [
-      d.appPubspec(),
-      d.dir("web", [
-        d.file(".outer.txt", "outer contents"),
-        d.dir(".dir", [
-          d.file("inner.txt", "inner contents"),
-        ])
-      ])
-    ]).create();
+    d.dir(
+        appPath,
+        [
+            d.appPubspec(),
+            d.dir(
+                "web",
+                [
+                    d.file(".outer.txt", "outer contents"),
+                    d.dir(".dir", [d.file("inner.txt", "inner contents"),])])]).create();
 
     pubServe();
     requestShould404(".outer.txt");
     requestShould404(".dir/inner.txt");
     endPubServe();
   });
 }