test: check endless loop while writing empty string

Refs: https://github.com/nodejs/node/pull/18673
PR-URL: https://github.com/nodejs/node/pull/18924
Refs: https://github.com/nodejs/node/pull/18673
Refs: https://github.com/nodejs/node/blob/v9.5.0/src/node_http2.cc#L1481-L1484
Refs: https://github.com/nodejs/node/blob/v9.5.0/lib/_http_outgoing.js#L659-L661


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>