Merge pull request w3c#3572 from saschanaz/patch-3

[css-images-4] Uncomment IDL attribtue

Author: tabatkins

css-images-4/Overview.bs

@@ -877,12 +877,10 @@ Using Out-Of-Document Sources: the <code>ElementSources</code> interface</h4>
 
 	<pre class='idl'>
 		partial namespace CSS {
-			// [SameObject] readonly attribute Map elementSources;
+			[SameObject] readonly attribute any elementSources;
 		};
 	</pre>
 
-	Issue(428): IDL namespaces don't support attributes yet.
-
 	Any entries in the <a idl>elementSources</a> map with a string key
 	and a value that is an object providing a <a>paint source</a>
 	are made available to the ''element()'' function.