[css-backgrounds-3] Match grammar of <<shadow>> to that of text-shadow/drop-shadow() and implementations. w3c#2305

Author: fantasai

css-backgrounds-3/Overview.bs

@@ -2748,7 +2748,7 @@ has been moved to the <a href="https://www.w3.org/TR/css3-break/">CSS Fragmentat
   represented by 2-4 length values, an optional color, and an optional ''box-shadow/inset'' keyword.
   Omitted lengths are 0; omitted colors default to the value of the 'color' property.
   <pre class=prod>
-  <dfn><<shadow>></dfn> = inset? &amp;&amp; <<length>>{2,4} &amp;&amp; <<color>>?</pre>
+  <dfn><<shadow>></dfn> = <<color>>? &amp;&amp; <<length>>{2,4} &amp;&amp; inset?</pre>
 
   <p>The components of each <<shadow>> are interpreted as follows:
 
@@ -3055,6 +3055,17 @@ The lists below describe which features from this specification are in each leve
 <h2 id="changes">
 Changes</h2>
 
+<h3 id="changes-2017-10">
+Changes since the 17 October 2017 Candidate Recommendation</h3>
+
+<ul>
+  <li>Inverted order of <<shadow>> grammar to match browser serialization and 'text-shadow'/''drop-shadow()''.
+      (<a href="https://github.com/w3c/csswg-drafts/issues/2305">Issue 2305</a>)
+      <blockquote>
+        <pre><dfn><<shadow>></dfn> = <del>inset</del><ins><<color>></ins>? &amp;&amp; <<length>>{2,4} &amp;&amp; <del><<color>></del><ins>inset</ins>?</pre>
+      </blockquote>
+</ul>
+
 <h3 id="changes-2014-09">
 Changes since the 9 September 2014 Candidate Recommendation</h3>