[css-shadow-parts] Remove Not Ready warning.

Author: tabatkins

css-shadow-parts/index.bs

@@ -8,7 +8,6 @@ Work Status: exploring
 URL: http://drafts.csswg.org/css-shadow-parts/
 Editor: Tab Atkins-Bittner, Google, http://xanthir.com/contact/
 Abstract: This specification defines the ''::part()'' and ''::theme()'' pseudo-elements on <a>shadow hosts</a>, allowing <a>shadow hosts</a> to selectively expose chosen elements from their <a>shadow tree</a> to the outside page for styling purposes.
-Warning: not ready
 </pre>
 
 <pre class=link-defaults>