If all parts of a table are non-standard display types, like all elements being display:block;, we weren't properly determining table cell indices because we weren't always taking into account thead, tbody, or tfoot elements. This patch:
* Exposes non-standard tbody, tfoot and thead elements as groupings, similar to ARIA rowgroup.
* Adjusts the one instance in nsAccessibilityService::CreateAccessible that didn't account for the table not being the direct parent of the row node, but the grandparent instead.
Differential Revision: https://phabricator.services.mozilla.com/D18333
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extra : moz-landing-system : lando
c27465e115