Need to handle long text inputs

[ahyatt]

In investigating https://github.com/ahyatt/emacs-websocket/issues/60, I looked at this package and tried to reproduce the error in it. I wasn't able to, because I found another issue: in atomic-chrome-on-message, it does not handle incomplete frames (frames in which completep is false). So it fails on parsing the frame as json, because you really have to combine two frames to read the completely json.

It's possible that we can solve this on the websocket side, but I'm hesitant to be combining frames, essentially faking frames, at least as a default behavior. So either way, something in this library would need to change. Let me know what seems reasonable to you. I can't promise a fix on the websocket side, because it might be infeasible for some reason, but I can at least look into it.