link-in-text-block should consider parent nodes & descending images

[WilcoFiers]

The following should pass the link-in-text-block rule:

<p>
  Lorem ipsum 
  <u><a href="#">dolor</a></u> 
  sit amet consectetur adipisicing elit. Ea officiis
  <a href="#"><img width="16" height="16"> exercitationem</a> 
  ullam inventore facere quaerat, itaque eaque. Eaque 
  <a href="#"><svg width="16" height="16"></svg>consectetur</a>,
  doloremque nostrum, vel animi quis pariatur, qui omnis inventore cum harum!
</p>

[straker]

This should pass for the 2 cases:

• link being wrapped by a u element
• link with graphical content (img, svg, canvas, object, etc.)