From: #6580 (comment)

By @tabatkins

For buttons and inputs, behavior seems inconsistent across browsers; in particular, it seems WebKit just treats buttons (and inputs) like any other box, so seems like that would be a reasonable direction to go in given the other browsers are very inconsistent? In any case, should be a separate issue if we need to address anything in the spec.

Doing this breaks this particular WPT test:
https://wpt.fyi/results/html/rendering/widgets/button-layout/abspos.html

This was added in:
web-platform-tests/wpt#14824
By @zcorpan , (primarily reviewed by @emilio )
whatwg/html#4143
whatwg/html#2948 (by @dholbert )
whatwg/html#4081 (comment)

etc.

Currently we (Blink) have different behaviour in the inline/block axis which we were about to fix (with zero insets, should still shrink-fit, instead of stretch).