function WebSocketServerSocket(pSocket) {
  this.pSocket_ = pSocket;
  this.readyState = 1;
  EventSource.apply(this);
  this.readFromSocket_();
}
Constructs a WebSocketServerSocket using the given socketId. This should be
a socket which has already been upgraded from an Http request.
@param {number} socketId The socket id with an active websocket connection.