assert: fix deepEqual inconsistencies

PR-URL: https://github.com/nodejs/node/pull/14491
Fixes: https://github.com/nodejs/node/issues/14441


Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Khaidi Chu <i@2333.moe>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>