sdk files reorganization to make dart2js a proper package

sdk/lib/_internal/compiler_runtime/lib/io_patch.dart

 // 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.
 
 import 'dart:_js_helper' show patch;
 
 @patch
 class _Directory {
   @patch
   static _current() {
@@ skipping 523 matching lines @@
   }
 }
 
 @patch
 class _IOService {
   @patch
   static Future _dispatch(int request, List data) {
     throw new UnsupportedError("_IOService._dispatch");
   }
 }