[css-pseudo-4] Drop UA stylesheet rule that was there from previous text-shadow model and is no longer needed. w3c#3932

Author: fantasai

css-pseudo-4/Overview.bs

@@ -541,8 +541,6 @@ Styling Highlights</h3>
     /* Represent default spelling/grammar error styling in an adjustable way */
     :root::spelling-error { text-decoration-line: spelling-error; }
     :root::grammar-error  { text-decoration-line: grammar-error; }
-    /* Ensure contrast on text with shadows */
-    :root::selection      { text-shadow: none; }
   </code></pre>
 
 <h3 id=highlight-bounds>
@@ -1006,6 +1004,7 @@ Changes</h2>
     uses the color that would be used if the text were not “highlighted”,
     even if that color was provided by a pseudo-element like ''::first-line''.
     (<a href="https://github.com/w3c/csswg-drafts/issues/4625">Issue 4625</a>)
+    <li>Define how 'text-shadow' interacts with [=highlight pseudo-elements=].
   </ul>
 
   Changes since the <a href="https://www.w3.org/TR/2016/WD-css-pseudo-4-20160607/">7 June 2016 Working Draft</a> include: