[CSS] Sign-Related Functions: abs() and sign()

[Rumyra]

Acceptance Criteria

• The listed features are documented sufficiently on MDN
• BCD is updated
• Interactive example and data repos are updated if appropriate
• The content has been reviewed as needed

For folks helping with Firefox related documentation

• Set bugs to dev-doc-complete
• Add entry to Firefox release notes if feature is enabled in release
• Add entry to Firefox experimental features page if feature is not yet enabled in release

Related Gecko bugs

https://bugzilla.mozilla.org/show_bug.cgi?id=1814588

Features to document

We already have some pages for these:

• abs()
• sign()

What's missing is BCD and Relnote.

Note that this brings it out of experimental status.

Related issues and pull requests

• Relnote: relnote(117): sign() and abs() functions nightly only (Planned Fx118) #28370
• BCD: relnote(117): sign() and abs() functions in nightly only (planned Fx118) browser-compat-data#20471

Other

• Check content open issues to see if any pertain to the subject matter. If there are any that can be closed because of the work, do so. If there are any that can be fixed relatively quickly because of the knowledge from completing this issue and you have time, feel free to go ahead and fix them.
• Check if glossary updates are required for the feature you're documenting - whether an existing term needs to be updated or a new term should be added.
• Check if BCD update means that content pages need to have experimental markup removed or deprecated markup added (front matter tags and macros).

[evilpie]

sign and abs are not enabled by default in 117. They are going to be shipped together with other new math functions in https://bugzilla.mozilla.org/show_bug.cgi?id=1814589.

[bsmth]

@evilpie - thank you for clarifying, BCD changes have already been merged, I'll amend shortly.

Copying from the bug for future me and others;

Specifically enabling these prefs (previously nightly only):
layout.css.round.enabled
layout.css.mod-rem.enabled
layout.css.exp.enabled
layout.css.abs-sign.enabled

[bsmth]

Amended BCD:

• relnote(117): sign() and abs() functions in nightly only (planned Fx118) browser-compat-data#20471

[bsmth]

As BCD & Relnote changes have landed, setting this as done now.

[bsmth]

All looks complete on this, closing as done now