Remove _BufferList from dart:io and now use BytesBuilder.

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 93 matching lines @@
                   });
               break;
 
             case _WebSocketOpcode.BINARY:
               if (_currentMessageType != _WebSocketMessageType.NONE) {
                 throw new WebSocketException("Protocol error");
               }
               _currentMessageType = _WebSocketMessageType.BINARY;
               _controller = new StreamController(sync: true);
               _controller.stream
-                  .fold(new _BufferList(), (buffer, data) => buffer..add(data))
+                  .fold(new BytesBuilder(), (buffer, data) => buffer..add(data))
                   .then((buffer) {
-                    sink.add(buffer.readBytes());
+                    sink.add(buffer.takeBytes());
                   }, onError: (error) {
                     sink.addError(error);
                   });
               break;
 
             case _WebSocketOpcode.CLOSE:
             case _WebSocketOpcode.PING:
             case _WebSocketOpcode.PONG:
               // Control frames cannot be fragmented.
               if (!_fin) throw new WebSocketException("Protocol error");
@@ skipping 687 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));
   }
 }