Get the RawServerSocketReference.
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 RawServerSocketReference can be used to create other
RawServerSockets listening on the same port,
using RawServerSocketReference.create.
Incoming connections on the port will be distributed fairly between the
active server sockets.
The RawServerSocketReference can be distributed to other isolates through
a RawSendPort.