Meta: dfn elements made interactive by html-dfn.js aren't keyboard accessible

[not-my-profile]

html-dfn.js was apparently forked from resources.whatwg.org/dfn.js, which was removed in whatwg/whatwg.org@4a772bd, so the other specs now use Bikeshed's built-in definition feature.

And Bikeshed indeed makes its dfn elements keyboard accessible, see e.g. the Node tree section of the DOM spec, pressing Tab twice there focuses Nodes because it's marked up as:

<dfn class="dfn-paneled has-dfn-panel" data-dfn-type="dfn" data-export="" id="concept-node"
   role="button" aria-expanded="false" tabindex="0">Nodes</dfn>

If you try the same in the HTML spec, it doesn't work because the markup of the dfn elements isn't changed, e.g:

<dfn id="reconsume">reconsume</dfn>