Add info about layout and bounds to generic

[carmacleod]

Resolves #1182.

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Preview | Diff

[carmacleod]

Very nice, @mcking65 !
I like having the most important info (i.e. "authors should not use generic") up front.
Also, "like presentation" and "unlike presentation" helps keep the generic vs presentation statements separate.
This is much more coherent now.

I made a few tiny editorial changes to your changes:

• added "or none" after the first instance of "presentation" (felt like it needed to be there)
• changed "a variety of other named containers such as group" to "a semantic container role such as group" because "named containers" and "named container" were in the same sentence and it felt redundant
• added "that" in "so that assistive technologies can..."

@jnurthen We should probably merge #1142 before merging this? It deletes the editor's note about triage of global properties, and makes aria-roledescription prohibited on generic (further differentiating generic from presentation).

[carmacleod]

@jnurthen @joanmarie @mcking65

This PR is ready for final review. The only changes are to the prose for generic role, and I have already incorporated Matt's editorial suggestions.

Here's the preview.

[joanmarie]

R+ BUT I did mention some nits that I'd like addressed (or at least considered).

[carmacleod]

@jnurthen Ready for final review.

pr-preview is timing out (I ran it a few times - will try again later), but here is the updated generic role prose after addressing @cookiecrook and @joanmarie's comments:

A nameless container element that has no semantic meaning on its own.

The generic role is intended for use as the implicit role of generic elements in host languages (such as HTML div or span), so is primarily for implementors of user agents. Authors SHOULD NOT use this role in content. Authors MAY use presentation or none to remove implicit accessibility semantics, or a semantic container role such as group to semantically group descendants in a named container.

Like an element with role presentation, an element with role generic can provide a limited number of accessible states and properties for its descendants, such as aria-live attributes. However, unlike elements with role presentation, generic elements are exposed in accessibility APIs so that assistive technologies can gather certain properties such as layout and bounds.

[carmacleod]

@jnurthen ping - build is passing and pr-preview is good.
Quick! Review this before something else breaks! 😄