Add v6Only named argument to ServerSocket and etc.

runtime/bin/socket_win.cc

 // 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.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_WINDOWS)
 
 #include "bin/builtin.h"
 #include "bin/eventhandler.h"
 #include "bin/file.h"
@@ skipping 221 matching lines @@
       i++;
     }
   }
   freeaddrinfo(info);
   return addresses;
 }
 
 
 intptr_t ServerSocket::CreateBindListen(RawAddr addr,
                                         intptr_t port,
-                                        intptr_t backlog) {
+                                        intptr_t backlog,
+                                        bool v6_only) {
   SOCKET s = socket(addr.ss.ss_family, SOCK_STREAM, IPPROTO_TCP);
   if (s == INVALID_SOCKET) {
     return -1;
   }
 
   BOOL optval = true;
   int status = setsockopt(s,
                           SOL_SOCKET,
                           SO_REUSEADDR,
                           reinterpret_cast<const char*>(&optval),
                           sizeof(optval));
   if (status == SOCKET_ERROR) {
     DWORD rc = WSAGetLastError();
     closesocket(s);
     SetLastError(rc);
     return -1;
   }
 
   if (addr.ss.ss_family == AF_INET6) {
-    optval = false;
+    optval = v6_only;
     setsockopt(s,
                IPPROTO_IPV6,
                IPV6_V6ONLY,
                reinterpret_cast<const char*>(&optval),
                sizeof(optval));
   }
 
   SocketAddress::SetAddrPort(&addr, port);
   status = bind(s,
                 &addr.addr,
@@ skipping 53 matching lines @@
                     IPPROTO_TCP,
                     TCP_NODELAY,
                     reinterpret_cast<char *>(&on),
                     sizeof(on)) == 0;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)