[css-images-4] Separate first and last stop fixing into separate steps, so it's clearer what happens with a single stop. w3c#10092

Author: svgeesus

css-images-4/Overview.bs

@@ -2047,6 +2047,8 @@ Color Stop “Fixup”</h4>
 		<li>
 			If the first <a>color stop</a> does not have a position,
 			set its position to 0%.
+
+		<li>
 			If the last <a>color stop</a> does not have a position,
 			set its position to 100%.