Revert "lib: lazy instantiation of fs.Stats dates"

This reverts commit 9836cf57.

Ref: https://github.com/npm/npm/issues/16734
PR-URL: https://github.com/nodejs/node/pull/13256


Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>