Use relative URIs for core library part-of statements.

sdk/lib/io/websocket.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.
 
-part of dart.io;
+part of "io.dart";
 
 /**
  * WebSocket status codes used when closing a WebSocket connection.
  */
 abstract class WebSocketStatus {
   static const int NORMAL_CLOSURE = 1000;
   static const int GOING_AWAY = 1001;
   static const int PROTOCOL_ERROR = 1002;
   static const int UNSUPPORTED_DATA = 1003;
   static const int RESERVED_1004 = 1004;
@@ skipping 399 matching lines @@
   void addUtf8Text(List<int> bytes);
 }
 
 class WebSocketException implements IOException {
   final String message;
 
   const WebSocketException([this.message = ""]);
 
   String toString() => "WebSocketException: $message";
 }