Remove old InputStream and OutputStream classes from dart:io.

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 57 matching lines @@
       }
     } catch (e) {
       // Only the interface implemented, _sink not available.
     }
   }
   return StdioType.OTHER;
 }
 
 
 class _StdIOUtils {
-  external static OutputStream _getStdioOutputStream(int fd);
-  external static InputStream _getStdioInputStream();
+  external static IOSink _getStdioOutputStream(int fd);
+  external static Stream<List<int>> _getStdioInputStream();
   external static int _socketType(nativeSocket);
 }