Load deferred chunks in the right order.

sdk/lib/_internal/lib/async_patch.dart

 // Copyright (c) 2012, 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.
 
 // Patch file for the dart:async library.
 
 import 'dart:_js_helper' show
     Primitives,
     convertDartClosureToJS,
     loadDeferredLibrary;
@@ skipping 15 matching lines @@
 }
 
 patch class _AsyncRun {
   patch static void _scheduleImmediate(void callback()) {
     // TODO(9002): don't use the Timer to enqueue the immediate callback.
     _createTimer(Duration.ZERO, callback);
   }
 }
 
 patch class DeferredLibrary {
-  patch Future<bool> load() {
+  patch Future<Null> load() {
     return loadDeferredLibrary(libraryName, uri);
   }
 }
 
 bool get _hasDocument => JS('String', 'typeof document') == 'object';