This is the first patch of bug 1684236 tweaked as per review comments.
Keeps us with one source of truth for reflowInput.
This could be cleaned up in the future if we manage to remove that
printing hack or what not.
Co-Authored-By: fantasai <fantasai.cvs@inkedblade.net>
Differential Revision: https://phabricator.services.mozilla.com/D181857