test: comparison operator now more strict

The 'equals' comparison operator was '==' instead of the
more strict '===', so it has been changed to be more strict

PR-URL: https://github.com/nodejs/node/pull/8190


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>