[css-color-4] Account for none alpha in premultiplication w3c#7253

Author: svgeesus

css-color-4/Overview.bs

@@ -4870,6 +4870,7 @@ Interpolating with alpha</h3>
 	they are transformed into <dfn export>premultiplied color values</dfn>
 	as follows:
 
+	*  If the alpha value is ''none'', the premultiplied value is the un-premultiplied value. Otherwise,
 	*  If any component value is ''none'', the premultiplied value is also ''none''.
 	*  For [=rectangular orthogonal color=] coordinate systems,
 		 all component values are multiplied by the alpha value.
@@ -4879,10 +4880,10 @@ Interpolating with alpha</h3>
 
 	To obtain a color value from a premultipled color value,
 
+	* If the interpolated alpha value is zero or ''none'',
+		the un-premultiplied value is the premultiplied value. Otherwise,
 	* If any component value is ''none'',
 		the un-premultiplied value is also ''none''.
-	* If the alpha value is zero,
-		the un-premultiplied value is the premultiplied value
 	* otherwise, each component which had been premultiplied
 		is divided by the interpolated alpha value.
 
@@ -5885,6 +5886,14 @@ parsing/relative-color-valid.html
 <h2 id='changes' class='no-num'>
 Changes</h2>
 
+<h3 id="changes-from-20220428">Changes since the
+	<a href="https://www.w3.org/TR/2022/WD-css-color-4-20220428/">Working Draft of 28 April 2022</a>
+</h3>
+
+<ul>
+	<!-- to 5 May 2022 -->
+	<li>Accounted for ''none'' alpha in premultiplication and un-premultiplication</li>
+
 <h3 id="changes-from-20211215">Changes since the
 	<a href="https://www.w3.org/TR/2021/WD-css-color-4-20211215/">Working Draft of 15 December 2021</a>
 </h3>