Guard a null ancestor when showing a hint popover - #13126

Check that ancestor is not null before reading its opened in popover mode when assigning the hint stack parent. The topmost popover ancestor algorithm can return null, including for a standalone hint popover.

Suggested regression coverage: showing a hint popover without an open popover ancestor, and showing one under an auto popover.

Spec: https://html.spec.whatwg.org/multipage/popover.html#show-popover

• 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: …
  • Deno (only for timers, structured clone, base64 utils, channel messaging, module resolution, web workers, and web storage): …
  • Node.js (only for timers, structured clone, base64 utils, channel messaging, and module resolution): …
• Corresponding HTML AAM & ARIA in HTML issues & PRs:
• MDN issue is filed: …
• The top of this comment includes a clear commit message to use.

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

/popover.html ( diff )