Remove dead code.

sdk/lib/io/stdio.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 int _STDIO_HANDLE_TYPE_TERMINAL = 0;
 const int _STDIO_HANDLE_TYPE_PIPE = 1;
 const int _STDIO_HANDLE_TYPE_FILE = 2;
 const int _STDIO_HANDLE_TYPE_SOCKET = 3;
@@ skipping 11 matching lines @@
                                         bool cancelOnError}) {
     return _stream.listen(
         onData,
         onError: onError,
         onDone: onDone,
         cancelOnError: cancelOnError);
   }
 }
 
 
-class _StdinEventSink implements EventSink<String> {
-  Function _add;
-  Function _addError;
-  Function _close;
-  _StdinEventSink(this._add, this._addError, this._close);
-
-  void add(String string) => _add(string);
-  void addError(errorEvent) => _addError(errorEvent);
-  void close() => _close();
-}
-
 /**
  * [Stdin] allows both synchronous and asynchronous reads from the standard
  * input stream.
  *
  * Mixing synchronous and asynchronous reads is undefined.
  */
 class Stdin extends _StdStream implements Stream<List<int>> {
   Stdin._(Stream<List<int>> stream) : super(stream);
 
   /**
@@ skipping 194 matching lines @@
   }
   return StdioType.OTHER;
 }
 
 
 class _StdIOUtils {
   external static IOSink _getStdioOutputStream(int fd);
   external static Stdin _getStdioInputStream();
   external static int _socketType(nativeSocket);
 }