[Web API] Expose effective zoom

[dipikabh]

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 for enabled/preview features
• Add/remove entry to Firefox experimental features page for preference/released features

Features to document

• Element.currentCSSZoom
• Spec: https://drafts.csswg.org/cssom-view-1/#dom-element-currentcsszoom

Related Gecko bugs

Bug 1880189: [css-viewport] [cssom] [css-typed-om] Consider adding a way of exposing the effective zoom

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.

[hamishwillee]

I think I understand this and have documented as such. However a couple of questions came up in review, so may need to modify. Tracking in https://bugzilla.mozilla.org/show_bug.cgi?id=1880189

Status:

• BCD
  • Updates for Firefox 126 beta browser-compat-data#22854
  • Element.currentCSSZoom - add doc link browser-compat-data#23009
• Docs
  • FF125 Element.currentCSSZoom add docs #33427
  • CSS zoom is standard #33457
• Release note FF126Relnote: Element.currentCSSZoom supported #33428
• dev-docs-complete

[dipikabh]

Thank you, Hamish!