Add MathML <a> handling to sanitization algorithms

[lukewarlow]

Add MathML <a> handling to sanitization algorithm

• At least two implementers are interested (and none opposed):
  • …
  • …
• Tests are written and can be reviewed and commented upon at:
  • …
• Implementation bugs are filed:
  • Chromium: …
  • Gecko: …
  • WebKit: …
• Corresponding HTML AAM & ARIA in HTML issues & PRs: N/A
• MDN issue is filed: …
• The top of this comment includes a clear commit message to use.

(See WHATWG Working Mode: Changes for more details.)

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/dynamic-markup-insertion.html ( diff )

[lukewarlow]

cc @fred-wang I think the mathml core spec needs to expose the href, hreflang, and type attribute definitions for the mathml a element, like SVG does.

[fred-wang]

@lukewarlow It seems the list of attributes for HTML and SVG is href, target, download, ping, rel, hreflang, type and referrerpolicy.

https://html.spec.whatwg.org/multipage/text-level-semantics.html#the-a-element
https://w3c.github.io/svgwg/svg2-draft/linking.html#AElement

I believe @tannal is also implementing some/all of these attributes in his CLs.

[lukewarlow]

Yes but only hreflang, type and href need referencing for now (as they're the ones that are safe for the more restricted sanitizer)

[zcorpan]

https://html.spec.whatwg.org/#inner-sanitize-steps currently sanitizes href and xlink:href on all MathML elements (since some previous MathML spec allowed any element to be a link).