test: replace assert.equal with assert.strictEqual

Using NodeTodo I learned of a need to swap out the .equal function
with .strictEqual in a few test files.

https://twitter.com/NodeTodo/status/803657321993961472
https://gist.github.com/Trott/864401455d4afa2428cd4814e072bd7c

additional commits squashed:
.strictEqual's argument signature is actual, expected, [message].
Previously some statements were listed as expected, actual.
As asked in PR i swapped them to match the correct argument signature.

PR-URL: https://github.com/nodejs/node/pull/9842


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>