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

sdk/lib/_internal/pub_generated/test/run/ignores_explicit_dart2js_transformer_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS 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 '../descriptor.dart' as d;
 import '../test_pub.dart';
 
 main() {
   initConfig();
   integration("doesn't choke on an explicit dart2js transformer", () {
-    d.dir(appPath, [
-      d.pubspec({
+    d.dir(appPath, [d.pubspec({
         "name": "myapp",
         "transformers": [r"$dart2js"]
       }),
-      d.dir("bin", [
-        d.file("script.dart", "main() => print('Hello!');")
-      ])
-    ]).create();
+          d.dir("bin", [d.file("script.dart", "main() => print('Hello!');")])]).create();
 
     var pub = pubRun(args: ["script"]);
     pub.stdout.expect("Hello!");
     pub.shouldExit(0);
   });
 }