feat(css): Update computed for border/column-rule/outline-width, outline-offset

[sb3nder]

Description

This PR updates the computed value for border-*-width, column-rule-width, outline-width, outline-offset, -webkit-border-*-width, to "the absolute length, snapped as a line width".

Motivation

Additional details

border-*-width, column-rule-width, outline-width snapped as a line width:
w3c/csswg-drafts#5210

Computed value untangled from *-style properties value:
w3c/csswg-drafts#11494 (comment)

outline-offset snapped as a line width:
w3c/csswg-drafts#12906

Definition of "length snapped as a line width":
w3c/csswg-drafts@c196082

Related issues and pull requests

TODO:
We need a doc link to explain "snapped as a line width", I will open an issue/pr in mdn/content.

Understand if I can add <line-width> to types.json, to make a page.

Maybe we need the translations for the computed value and link title attribute:

the absolute length, snapped as a line width

To snap a <length> len as a line width:

1. If len is an integer number of device pixels, leave it as is.
2. If the absolute value of len is greater than zero, but less than 1 device pixel, round it away from zero to ±1 device pixel.
3. If the absolute value of len is greater than 1 device pixel, round it towards zero to the nearest integer number of device pixels.