chromium/content/test/data/accessibility/html/relevant-space.html

<!-- An extra empty span between actual content and the space -->
<p>
  <span>A(</span><span></span> <span>)B</span>
</p>
<!-- Normally we can ignore space before a br  -->
<p>
  <span>C(</span><span><span> <br></span></span><span>)D</span>
</p>
<!-- Google Docs end-of line markup that is used to simulate a soft line break while forcing a line break with <br>.
     Do not ignore the space next to the <br> as it is marked role=presentation and won't be exposed -->
<p>
  <span>E(</span><span><span contenteditable="false"> <br role="presentation"></span></span><span>)F</span>
</p>