Move dart:chrome to dart:_chrome.

tools/dom/src/chrome/custom_dart/app_window.create.dart

Index: tools/dom/src/chrome/custom_dart/app_window.create.dart
===================================================================
--- tools/dom/src/chrome/custom_dart/app_window.create.dart	(revision 27851)
+++ tools/dom/src/chrome/custom_dart/app_window.create.dart	(working copy)
@@ -1,16 +0,0 @@
-// Copyright (c) 2013, 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.
-
-// TODO(sashab): This override is no longer needed once prefixes are removed.
-void create(String url,
-            [AppWindowCreateWindowOptions options,
-            void callback(AppWindowAppWindow created_window)]) {
-  void __proxy_callback(created_window) {
-    if (callback != null)
-      callback(new AppWindowAppWindow._proxy(created_window));
-  }
-  JS('void', '#.create(#, #, #)', this._jsObject, url, convertArgument(options),
-     convertDartClosureToJS(__proxy_callback, 1));
-}
-