Proposed IDL updates to section 6.3 ARIA Attributes

[rahimabdi]

Describe the change

CC @annevk

I'd like to propose several updates to section 6.3 ARIA Attributes:

1. During the June 27 2024 "undefined" deep dive discussion, the ARIA WG largely agreed that the following note in section 6.3.4 ARIA nullable DOMString Attribute should be removed because it is no longer relevant (since the ARIA IDL shipped in ARIA v1.2 with nullable DOMStrings, this note may be outdated and unplanned as a future update):

Note: As of ARIA 1.2, all ARIA attributes exposed via IDL are defined as nullable DOMStrings. This matches the current implementation of all major rendering engines. This specification change should result in no implementation changes; it will merely represent the current reality of web engines. However, in a future draft, the ARIA Working Group intends to change several ARIA attributes to non-nullable DOMStrings, and seek implementations. The proposed change will bring ARIA into alignment with the HTML’s usage of enumerated attributes.

2. Update spec language to specify that ARIA IDL attributes reflect as multiple types (not just nullable DOMString), including Element and FrozenArray<Element>. This would also address https://github.com/w3c/aria/issues/1763.

3. Provide undefined value assignment examples in section 6.3.4.1 Example Attribute Usage.

Link to the version of the specification or documentation you were looking at

Link to documentation: https://w3c.github.io/aria/#aria-attributes

Does the issue exists in the editors draft (the editors draft is the most recent draft of the specification)?

Yes.