Link to issue number:

#13391
#13106

Summary of the issue:

Details summary can not be reported in firefox browse mode.

Description of how this pull request fixes the issue:

Firefox does not yet expose the IA2 attribute "details-roles", used a proxy / optimization for fetching details relations.
The absence of this prevented the details summary being fetched.
Instead, use the existence of details relations to confirm.

Testing strategy:

Using code pen - editor or code pen - fullpage
Manual testing in Firefox

Known issues with pull request:

None

Change log entries:

None

Code Review Checklist:

• Pull Request description:
  • description is up to date
  • change log entries
• Testing:
  • Unit tests
  • System (end to end) tests
  • Manual testing
• API is compatible with existing add-ons.
• Documentation:
  • User Documentation
  • Developer / Technical Documentation
  • Context sensitive help for GUI changes
• UX of all users considered:
  • Speech
  • Braille
  • Low Vision
  • Different web browsers
  • Localization in other languages / culture than English