[DevTools/CSS] New inactive CSS warnings in the rules view

[chrisdavidmills]

Acceptance criteria

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

Features to document

1. New warnings for inactive CSS properties in rules view

Related Gecko bugs

1. • [Inactive CSS] Display a warning when table-layout is used incorrectly
2. • [Inactive CSS] Incorrect warning for text-overflow: ellipsis
3. • [Inactive CSS] Display a warning when scroll-padding-* properties are used on a non-scrollable element

This is a devtools thing — the rules view shows inactive rules as greyed out (with tooltips, I think?) As far as I am aware, we don't document what inactive rule warnings are available in Fx. I'm wondering if we should just add a rel note for the two. If you decide that something more substantial would be useful, then perhaps getting Rachel involved would be useful.

For folks helping with Firefox-related documentation features — make sure above AC have been done, but also:

• 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

[hamishwillee]

@rachelandrew This is really "devtools". Feel free to take it, but if you wanted to hand something over this would be it.

[rachelandrew]

Ah sorry - I just batched assigned all the ones marked CSS to me to look at this week, feel free to grab it!

[hamishwillee]

@rachelandrew Never a problem if you grab something I might otherwise have to work on :-). It's just that I think your queue is bigger than mine.

[hamishwillee]

1. • BCD is updated - NA
2. • Interactive example and data repos are updated if appropriate - NA
3. • Docs - NA no actual "specific" docs required
4. • Release note

@chrisdavidmills We don't document the inactive rules individually in the Page Inspector - we just say that if they are inactive they are greyed out maybe with a warning (which makes sense - people trust the feature). So there is no real new documentation for this other than to note the bug fixes.

@SebastianZ added some release release notes, however I have done a "tweak" of these in #2763 - Essentially this groups them together under an explanation that they all belong to the Page inspector.

Read for review.