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

sdk/lib/_internal/pub_generated/test/dart2js/supports_valid_options_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 file.
 
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import '../serve/utils.dart';
 
 main() {
   initConfig();
   integration("supports most dart2js command-line options", () {
-    d.dir(appPath, [
-      d.pubspec({
+    d.dir(appPath, [d.pubspec({
         "name": "myapp",
         "transformers": [{
-          "\$dart2js": {
-            "commandLineOptions": ["--enable-diagnostic-colors"],
-            "checked": true,
-            "csp": true,
-            "minify": true,
-            "verbose": true,
-            "environment": {"name": "value"},
-            "suppressWarnings": true,
-            "suppressHints": true,
-            "suppressPackageWarnings": false,
-            "terse": true
-          }
-        }]
+            "\$dart2js": {
+              "commandLineOptions": ["--enable-diagnostic-colors"],
+              "checked": true,
+              "csp": true,
+              "minify": true,
+              "verbose": true,
+              "environment": {
+                "name": "value"
+              },
+              "suppressWarnings": true,
+              "suppressHints": true,
+              "suppressPackageWarnings": false,
+              "terse": true
+            }
+          }]
       }),
-      d.dir("web", [
-        d.file("main.dart", "void main() => print('Hello!');")
-      ])
-    ]).create();
+          d.dir(
+              "web",
+              [d.file("main.dart", "void main() => print('Hello!');")])]).create();
 
     // None of these options should be rejected, either by pub or by dart2js.
     pubServe();
     requestShouldSucceed("main.dart.js", isNot(isEmpty));
     endPubServe();
   });
 }