Add support for text-box (text-box-trim, text-box-edge) CSS properties.

[Malien]

https://developer.mozilla.org/en-US/docs/Web/CSS/text-box
https://caniuse.com/mdn-css_properties_text-box
https://css-tricks.com/two-css-properties-for-trimming-text-box-whitespace/

The support has landed in Safari 18.2 and Chrome 133.

Allows us to align stuff easily with the ascendants, descendants, baseline, etc.

vs

It degrades gracefully on unsupported browsers (a bit uglier layout in rare-ish circumstances).

It is pretty fresh off the release. There aren't really common ways to use it now. The most common proprety combination I've seen is text-box: trim-both cap