Pass in is value

dom.bs

@@ -6775,7 +6775,7 @@ invoked, must run these steps:
    <li><p>Let <var>definition</var> be the result of
    <a lt="look up a custom element definition">looking up a custom element definition</a> given
    <a>context object</a>'s <a for=Node>node document</a>, its <a for=Element>namespace</a>, its
-   <a for=Element>local name</a>, and null as <a><code>is</code> value</a>.
+   <a for=Element>local name</a>, and its <a for=Element><code>is</code> value</a>.
 
    <li><p>If <var>definition</var> is not null and <var>definition</var>'s
    <a for="custom element definition">disable shadow</a> is true, then <a>throw</a> a