Because the ARIA form role is a landmark, it should be mapped to ATK_ROLE_LANDMARK; not ATK_ROLE_FORM. https://rawgit.com/w3c/aria/master/core-aam/core-aam.html#role-map-form
<rdar://problem/34914168>
Created attachment 323323 [details] Patch
Comment on attachment 323323 [details] Patch Clearing flags on attachment: 323323 Committed r223145: <http://trac.webkit.org/changeset/223145>
All reviewed patches have been landed. Closing bug.