Make IOSink implement StringSink

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);
       case _STDIO_HANDLE_TYPE_FILE:
         return 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);
       case _STDIO_HANDLE_TYPE_FILE:
-        return new IOSink(new _FileStreamConsumer.fromStdio(fd));
+        return new IOSink(new _FileStreamConsumer.fromStdio(fd),
+                          Encoding.ASCII);
       default:
         throw new FileIOException("Unsupported stdin type");
     }
   }
 
   static int _socketType(nativeSocket) {
     return _getSocketType(nativeSocket);
   }
 }
 
 
 _getStdioHandle(_NativeSocket socket, int num) native "Socket_GetStdioHandle";
 _getStdioHandleType(int num) native "File_GetStdioHandleType";
 _getSocketType(_NativeSocket nativeSocket) native "Socket_GetType";