[css-2020] Add 'aspect-ratio' to cleared-for-shipping list.

Author: fantasai

css-2020/Overview.bs

@@ -717,7 +717,9 @@ Safe to Release pre-CR Exceptions</h2>
                <li>The ''min-content'' and ''max-content'' keywords of the sizing properties.
                See <a href="https://lists.w3.org/Archives/Public/www-style/2015Aug/0109.html">decision</a>
                and <a href="https://www.w3.org/TR/css-sizing-3/#sizing-values">specification</a>.
-	       <li>The ''conic-gradient()'' gradient notation. See <a href="https://github.com/w3c/csswg-drafts/issues/2383#issuecomment-371340088">decision</a>.
+               <li>The ''conic-gradient()'' gradient notation. See <a href="https://github.com/w3c/csswg-drafts/issues/2383#issuecomment-371340088">decision</a>.
+
+               <li>The 'aspect-ratio' property. [[!CSS-SIZING-4]]
        </ul>
 
        The following features have been explicitly and retroactively cleared