test: add test case of PassThrough

This commit adds the test case of PassThrough.
This test case checks that PassThrough can
construct without new operator.

This is a part of Code And Learn at NodeFest 2016

Fixes: https://github.com/nodejs/code-and-learn/issues/58
PR-URL: https://github.com/nodejs/node/pull/9581


Reviewed-By: Yosuke Furukawa <yosuke.furukawa@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Shigeki Ohtsu <ohtsu@ohtsu.org>