Notify web socket readers when socket is closed becaus no pong received.

[Alexibu]

When a web socket client disappears with out closing the socket nicely, the ping / pong mechanism is designed to detect this. It does detect it and closes the socket, but if there are readers waiting for messages they receive no notification and stay reading.
This change notifies the readers, so they get a socket closed exception.
Close already stops the timer so the call to stop the timer was redundant.

[s-ludwig]

Good catch, I remember sometimes seeing a kind of memory leak when web sockets were involved. Can you cherry pick your last commit into a new branch and use that for the PR, though? It has picked up the previous cookie changes, too.