[css-color-4][editorial] Try using wpt pathprefix attribute

Author: svgeesus

css-color-4/Overview.bs

@@ -761,7 +761,10 @@ Transparency: the 'opacity' property</h3>
 		tagged-images-002.html
 		tagged-images-003.html
 		tagged-images-004.html
-		/png/cicp-chunk.html
+	</wpt>
+
+	<wpt pathprefix="/png">
+		cicp-chunk.html
 	</wpt>
 
 	If the color profile or other identifying information is invalid, the image is treated as [=untagged images=]