aquatic_ws: polling: don't check if event readable

We only register interest in readable events so this should be OK

TODO.md

@@ -1,8 +1,6 @@
 # TODO
 
 ## aquatic_ws
-* is it even necessary to check if event is readable in poll, since that
-  is all we're listening for?
 * add sensible logging method, maybe stderrlog with quiet as default
 
 ## aquatic_udp

aquatic_ws/src/lib/network/mod.rs

@@ -97,7 +97,7 @@ pub fn run_poll_loop(
                     valid_until,
                     &mut poll_token_counter,
                 );
-            } else if event.is_readable(){
+            } else {
                 run_handshakes_and_read_messages(
                     socket_worker_index,
                     &in_message_sender,