Fix Mac OS check for terminal input

runtime/bin/socket_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 RawServerSocket {
   /* patch */ static Future<RawServerSocket> bind(address,
                                                   int port,
                                                   {int backlog: 0,
                                                    bool v6Only: false,
                                                    bool shared: false}) {
@@ skipping 1225 matching lines @@
     native.isClosedRead = true;
     native.closedReadEventSent = true;
     return new _RawSocket(native);
   }
 
   factory _RawSocket._readPipe(int fd) {
     var native = new _NativeSocket.pipe();
     native.isClosedWrite = true;
     if (fd != null) _getStdioHandle(native, fd);
     var result = new _RawSocket(native);
-    result._isMacOSTerminalInput =
-        Platform.isMacOS &&
-        _StdIOUtils._socketType(result._socket) == _STDIO_HANDLE_TYPE_TERMINAL;
+    if (fd != null) {
+      var socketType = _StdIOUtils._socketType(result._socket);
+      result._isMacOSTerminalInput =
+          Platform.isMacOS && socketType == _STDIO_HANDLE_TYPE_TERMINAL;
+    }
     return result;
   }
 
   StreamSubscription<RawSocketEvent> listen(void onData(RawSocketEvent event),
                                             {Function onError,
                                              void onDone(),
                                              bool cancelOnError}) {
     return _controller.stream.listen(
         onData,
         onError: onError,
@@ skipping 585 matching lines @@
 Datagram _makeDatagram(List<int> data,
                        String address,
                        List<int> in_addr,
                        int port) {
   return new Datagram(
       data,
       new _InternetAddress(address, null, in_addr),
       port);
 }