Use native async/await support in pub.

sdk/lib/_internal/pub_generated/test/dart2js/does_not_compile_until_its_output_is_requested_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.
-
-import 'package:scheduled_test/scheduled_stream.dart';
-
-import '../descriptor.dart' as d;
-import '../test_pub.dart';
-import '../serve/utils.dart';
-
-main() {
-  initConfig();
-  integration("does not compile until its output is requested", () {
-    d.dir(appPath, [d.pubspec({
-        "name": "myapp",
-        "version": "0.0.1",
-      }),
-          d.dir("web", [d.file("syntax-error.dart", "syntax error")])]).create();
-
-    var server = pubServe();
-    server.stdout.expect("Build completed successfully");
-
-    // Once we request the output, it should start compiling and fail.
-    requestShould404("syntax-error.dart.js");
-    server.stdout.expect(
-        emitsLines(
-            "[Info from Dart2JS]:\n" "Compiling myapp|web/syntax-error.dart..."));
-    server.stdout.expect(consumeThrough("Build completed with 1 errors."));
-    endPubServe();
-  });
-}