Add the index information to network interface

sdk/lib/io/socket.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;
 
 
 /**
  * [InternetAddressType] is the type an [InternetAddress]. Currently,
  * IP version 4 (IPv4) and IP version 6 (IPv6) are supported.
@@ skipping 127 matching lines @@
  * system. It contains a list of [InternetAddress]s, that's bound to the
  * interface.
  */
 abstract class NetworkInterface {
   /**
    * Get the name of the [NetworkInterface].
    */
   String get name;
 
   /**
+   * Get the index of the [NetworkInterface].
+   */
+  String get index;
+
+  /**
    * Get a list of [InternetAddress]s currently bound to this
    * [NetworkInterface].
    */
   List<InternetAddress> get addresses;
 
   /**
    * Query the system for [NetworkInterface]s.
    *
    * If [includeLoopback] is `true`, the returned list will include the
    * loopback device. Default is `false`.
@@ skipping 367 matching lines @@
     }
     if (address != null) {
       sb.write(", address = ${address.host}");
     }
     if (port != null) {
       sb.write(", port = $port");
     }
     return sb.toString();
   }
 }