Wrap stdout/stderr/stdin to only expose the relevant methods.

runtime/bin/stdio_patch.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.
 
 patch class _StdIOUtils {
   static Stream<List<int>> _getStdioInputStream() {
     switch (_getStdioHandleType(0)) {
       case _STDIO_HANDLE_TYPE_TERMINAL:
       case _STDIO_HANDLE_TYPE_PIPE:
       case _STDIO_HANDLE_TYPE_SOCKET:
-        return new _Socket._readPipe(0);
+        return new _Stdin(new _Socket._readPipe(0));
       case _STDIO_HANDLE_TYPE_FILE:
-        return new _FileStream.forStdin();
+        return new _Stdin(new _FileStream.forStdin());
       default:
         throw new FileIOException("Unsupported stdin type");
     }
   }
 
   static IOSink _getStdioOutputStream(int fd) {
     assert(fd == 1 || fd == 2);
     switch (_getStdioHandleType(fd)) {
       case _STDIO_HANDLE_TYPE_TERMINAL:
       case _STDIO_HANDLE_TYPE_PIPE:
       case _STDIO_HANDLE_TYPE_SOCKET:
-        return new _Socket._writePipe(fd);
+        return new _StdSink(new _Socket._writePipe(fd));
       case _STDIO_HANDLE_TYPE_FILE:
-        return new IOSink(new _FileStreamConsumer.fromStdio(fd));
+        return new _StdSink(new IOSink(new _FileStreamConsumer.fromStdio(fd)));
       default:
         throw new FileIOException("Unsupported stdin type");
     }
   }
 
   static int _socketType(nativeSocket) {
     var result = _getSocketType(nativeSocket);
     if (result is OSError) {
       throw new FileIOException("Error retreiving socket type", result);
     }
     return result;
   }
 }
 
 
 _getStdioHandle(_NativeSocket socket, int num) native "Socket_GetStdioHandle";
 _getStdioHandleType(int num) native "File_GetStdioHandleType";
 _getSocketType(_NativeSocket nativeSocket) native "Socket_GetType";