test: check noop function invocations

In test/pummel/test-stream2-basic.js, check that noop functions are
called the expected number of times.

PR-URL: https://github.com/nodejs/node/pull/13146


Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>