Use native async/await support in pub.

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

Index: sdk/lib/_internal/pub_generated/test/serve/does_not_serve_hidden_assets_test.dart
diff --git a/sdk/lib/_internal/pub_generated/test/serve/does_not_serve_hidden_assets_test.dart b/sdk/lib/_internal/pub_generated/test/serve/does_not_serve_hidden_assets_test.dart
deleted file mode 100644
index 26981c1e5900a3a5653c1fd3aece1256ffe08668..0000000000000000000000000000000000000000
--- a/sdk/lib/_internal/pub_generated/test/serve/does_not_serve_hidden_assets_test.dart
+++ /dev/null
@@ -1,29 +0,0 @@
-// 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();
-
-    pubServe();
-    requestShould404(".outer.txt");
-    requestShould404(".dir/inner.txt");
-    endPubServe();
-  });
-}