Consider allowing roles on <area> with no href attribute

[scottaohara]

Creating this issue to replace #317, as there is no need to resolve that issue for 1.0 specification, but we should consider this suggestion going forward.

<a> with no href takes any role, but <area> with no href takes no roles. These are similar and seem like they should be consistent. <area role=button> seems like it would be useful, as would checkbox and other widget roles.

[scottaohara]

Spent quite a bit of time reviewing this today. Due to the area element's inability to be styled effectively, that it cannot contain any child elements (save for css pseudo-element content - but even that doesn't render near the actual area, but rather adjacent to the image map)... i really don't see how this would be a good change. though the concept of a and area without href are similar, the actual rendered result is quite different.

That said I can see a potential use case of allowing role=button or role=link (ideally with tabindex=0, but there can also be legitimate use cases for needing to expose these roles but not wanting them in the tab order - per other elements that perform the same functionality).

cc @stevefaulkner and @patrickhlauke, what say you two on this?

[patrickhlauke]

discussed at meeting today with @scottaohara and @stevefaulkner - agreed to allow role="button" and role="link" (with tabindex="0") but not other roles due to weird browser behaviour/treatment of <area>

[scottaohara]

specifically due to the fact that no styling is allowed for these elements, or allow for nested content in away that would make sense for any other role here.