title: Firefox does not allow to focus anchor tag with role button
body: <p>In Firefox if I specify an <code>&lt;a role="button" tabindex="0"&gt;Something&lt;/a&gt;</code> I couldn't find a way how to make this element focusable by <kbd>Tab</kbd>.</p>
  
  <p>In Safari/Chrome it works as expected. But in Firefox it doesn't work unless I change it to <code>&lt;div role="button" tabindex="0"&gt;Something&lt;/div&gt;</code>.</p>
  
  <p>When I look to accessibility tools I can see that in both cases the role is <code>pushbutton</code> but Firefox completely ignores <code>&lt;a&gt;</code>. Is this a bug in Firefox or am I missing something?</p>
  
  <p>I'm on Mac OS so I know that it depends on settings but if Safari is able to focus given element how come that Firefox doesn't?</p>