r.js timeout is broken and server stops responding

[CMogilko]

The docs https://rethinkdb.com/api/javascript/js/ say that default timeout for r.js() is 5 secs.
But this query r.js("while(true) {}") doesn't timeouts. Build today from the next branch. But it works in rethinkdb-legacy.

[CMogilko]

It is more. After this query server doesn't respond at all. Ctrl-C can't help with stopping server. Only kill helps.

[asakatida]

This is an issue discussed during the migration to Duktape see #5. There is a preview hook that needs to be setup for timeouts.

[asakatida]

Exact fix is stubbed in code https://github.com/grandquista/rebirthdb/blob/next/src/extproc/js_job.cc#L34.