Fix a number of issues with determining the type of stdio

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;
-const int _STDIO_HANDLE_TYPE_OTHER = -1;
+const int _STDIO_HANDLE_TYPE_OTHER = 4;
 
 
 class StdioType {
   static const StdioType TERMINAL = const StdioType._("terminal");
   static const StdioType PIPE = const StdioType._("pipe");
   static const StdioType FILE = const StdioType._("file");
   static const StdioType OTHER = const StdioType._("other");
+  final String name;
   const StdioType._(String this.name);
-  final String name;
+  String toString() => "StdioType: $name";
 }
 
 
 Stream<List<int>> _stdin;
 IOSink _stdout;
 IOSink _stderr;
 
 
 Stream<List<int>> get stdin {
   if (_stdin == null) {
@@ skipping 25 matching lines @@
   }
   if (object is Socket) {
     switch (_StdIOUtils._socketType(object._nativeSocket)) {
       case _STDIO_HANDLE_TYPE_TERMINAL: return StdioType.TERMINAL;
       case _STDIO_HANDLE_TYPE_PIPE: return StdioType.PIPE;
       case _STDIO_HANDLE_TYPE_FILE:  return StdioType.FILE;
     }
   }
   if (object is IOSink) {
     try {
-      if (object._sink.target is _FileStreamConsumer) {
+      if (object._target is _FileStreamConsumer) {
         return StdioType.FILE;
       }
     } catch (e) {
       // Only the interface implemented, _sink not available.
     }
   }
   return StdioType.OTHER;
 }
 
 
 class _StdIOUtils {
   external static IOSink _getStdioOutputStream(int fd);
   external static Stream<List<int>> _getStdioInputStream();
   external static int _socketType(nativeSocket);
 }