Revert "Switch libraries to using new tags."

sdk/lib/io/http_session.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;
-
 const String _DART_SESSION_ID = "DARTSESSID";
 
 // A _HttpSession is a node in a double-linked list, with _next and _prev being
 // the previous and next pointers.
 class _HttpSession implements HttpSession {
   _HttpSession(_HttpSessionManager this._sessionManager, String this.id)
     : _lastSeen = new Date.now();
 
   void destroy() {
     _destroyed = true;
@@ skipping 135 matching lines @@
 
   Map<String, _HttpSession> _sessions;
   int _sessionTimeout = 20 * 60;  // 20 mins.
   _HttpSession _head;
   _HttpSession _tail;
   Timer _timer;
 
   external static Uint8List _getRandomBytes(int count);
 }