<Bug> Skip accessibility checking for an element with an inert attribute and its descendants

[shunguoy]

The inert attribute is an HTML global attribute that indicates that a browser ignores any user event or interaction for the element and its descendants. An inert element and its descendants get removed from the tab order and accessibility tree.

https://html.spec.whatwg.org/multipage/interaction.html#modal-dialogs-and-inert-subtrees
https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/inert

Currently, the checker reports accessibility issues for an inert element and its descendants, which is a false positive.

An example from HTML 5 spec:

<section aria-labelledby=s1>
  <h3 id=s1>Population by City</h3>
  <div class=container>
    <div class=loading><p>Loading...</p></div>
    <div inert>
      <form>
        <fieldset>
          <legend>Date range</legend>
          <div>
            <label for=start>Start</label>
            <input type=date id=start>
          </div>
          <div>
            <label for=end>End</label>
            <input type=date id=end>
          </div>
          <div>
            <button>Apply</button>
          </div>
        </fieldset>
      </form>
      <table>
        <caption>From 20-- to 20--</caption>
        <thead>
          <tr>
            <th>City</th>
            <th>State</th>
            <th>20-- Population</th>
            <th>20-- Population</th>
            <th>Percentage change</th>
          </tr>
        </thead>
        <tbody>
          <!-- ... -->
        </tbody>
      </table>
    </div>
  </div>
</section>

[shunguoy]

triage: skip the check for the entire section in the engine