@aria-controls should be exposed in AXLinkedUIElements Not sure if this is a regression, but it doesn't look like the layout test actually tests anything related to @aria-controls. It just tests the roles and @aria-selected. LayoutTests/accessibility/aria-controls-with-tabs.html
<rdar://problem/13589004>
Related https://bugs.webkit.org/show_bug.cgi?id=30842