Revert "Switch libraries to using new tags."

sdk/lib/io/common.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.
 
-part of dart.io;
-
 // Constants used when working with native ports.
 const int _SUCCESS_RESPONSE = 0;
 const int _ILLEGAL_ARGUMENT_RESPONSE = 1;
 const int _OSERROR_RESPONSE = 2;
 const int _FILE_CLOSED_RESPONSE = 3;
 
 const int _ERROR_RESPONSE_ERROR_TYPE = 0;
 const int _OSERROR_RESPONSE_ERROR_CODE = 1;
 const int _OSERROR_RESPONSE_MESSAGE = 2;
 
@@ skipping 73 matching lines @@
 
 
 // TODO(ager): The only reason for the class here is that
 // we cannot patch a top-level function.
 class _BufferUtils {
   // Check if a List is a builtin VM List type. Returns true
   // if the List is a builtin VM List type and false if it is
   // a user defined List type.
   external static bool _isBuiltinList(List buffer);
 }