Disable keep alive checks in long polling transport - JS

#3259
What is the semantics of "ConnectionTimeout"? I can see that the functionality of timing out the poll is currently split between the server and the client. What's not clear to me is what the ConnectionTime out is supposed to be. If the logic was not split between the server and the client it would be clear if the setting applies to clients in general (in which case it would be the server side things) or if it applies to a particular client (in which case it would be calculated by the client (using the DisconnectTimeout)).