Remove usage of dart:utf from dart:io.

sdk/lib/io/websocket_impl.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;
 
 const String _webSocketGUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
 
 class _WebSocketMessageType {
   static const int NONE = 0;
@@ skipping 77 matching lines @@
               }
               break;
 
             case _WebSocketOpcode.TEXT:
               if (_currentMessageType != _WebSocketMessageType.NONE) {
                 throw new WebSocketException("Protocol error");
               }
               _currentMessageType = _WebSocketMessageType.TEXT;
               _controller = new StreamController(sync: true);
               _controller.stream
-                  .transform(new Utf8DecoderTransformer(null))
+                  .transform(UTF8.decoder)
                   .fold(new StringBuffer(), (buffer, str) => buffer..write(str))
                   .then((buffer) {
                     sink.add(buffer.toString());
                   }, onError: (error) {
                     sink.addError(error);
                   });
               break;
 
             case _WebSocketOpcode.BINARY:
               if (_currentMessageType != _WebSocketMessageType.NONE) {
@@ skipping 188 matching lines @@
         closeCode = WebSocketStatus.NO_STATUS_RECEIVED;
         if (_controlPayload.length > 0) {
           if (_controlPayload.length == 1) {
             throw new WebSocketException("Protocol error");
           }
           closeCode = _controlPayload[0] << 8 | _controlPayload[1];
           if (closeCode == WebSocketStatus.NO_STATUS_RECEIVED) {
             throw new WebSocketException("Protocol error");
           }
           if (_controlPayload.length > 2) {
-            closeReason = _decodeUtf8Strict(_controlPayload.sublist(2));
+            closeReason = UTF8.decode(_controlPayload.sublist(2));
           }
         }
         _state = CLOSED;
         sink.close();
         break;
 
       case _WebSocketOpcode.PING:
         sink.add(new _WebSocketPing(_controlPayload));
         break;
 
@@ skipping 556 matching lines @@
            (code < WebSocketStatus.NORMAL_CLOSURE ||
             code == WebSocketStatus.RESERVED_1004 ||
             code == WebSocketStatus.NO_STATUS_RECEIVED ||
             code == WebSocketStatus.ABNORMAL_CLOSURE ||
             (code > WebSocketStatus.INTERNAL_SERVER_ERROR &&
              code < WebSocketStatus.RESERVED_1015) ||
             (code >= WebSocketStatus.RESERVED_1015 &&
              code < 3000));
   }
 }