test: fix the arguments order in assert.strictEqual

I working at "Code and Learn" on Node fest 2018 in Japan.

Refs: https://github.com/nodejs/node/pull/24431

PR-URL: https://github.com/nodejs/node/pull/24624


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Shingo Inoue <leko.noor@gmail.com>
Reviewed-By: Masashi Hirano <shisama07@gmail.com>