Get the ServerSocketReference.
WARNING: This feature is highly experimental and currently only
works on Linux. The API will be removed in Dart 1.10. Use the
shared optional argument on the bind method instead.
The returned ServerSocketReference can be used to create other ServerSockets listening on the same port, using ServerSocketReference.create. Incoming connections on the port will be distributed fairly between the active server sockets. The ServerSocketReference can be distributed to other isolates through a SendPort.