Accessibility mapping for obsolete elements

[zcorpan]

See whatwg/html#9296

HTML specifies obsolete features here https://html.spec.whatwg.org/multipage/obsolete.html#non-conforming-features

These seem like it would be beneficial for users to map:

User agents must treat acronym elements in a manner equivalent to abbr elements in terms of semantics and for purposes of rendering.
User agents must treat dir elements in a manner equivalent to ul elements in terms of semantics and for purposes of rendering.
User agents must treat listing elements in a manner equivalent to pre elements in terms of semantics and for purposes of rendering.
User agents must treat plaintext elements in a manner equivalent to pre elements in terms of semantics and for purposes of rendering.
User agents must treat xmp elements in a manner equivalent to pre elements in terms of semantics and for purposes of rendering.

Not covered in HTML but maybe should be:

• frame (like iframe)
• strike (like s)