Fix #240. Attributes, by default, are not namespaced. (#243)

Author: koto

dist/spec/index.html

@@ -824,7 +824,7 @@ <h4 class="heading settled" data-level="2.3.1" id="trusted-type-policy-factory">
        <li data-md>
         <p>If <var>elementNs</var> is an empty string, set <var>elementNs</var> to <a data-link-type="dfn" href="https://infra.spec.whatwg.org/#html-namespace" id="ref-for-html-namespace①">HTML namespace</a>.</p>
        <li data-md>
-        <p>If <var>attrNs</var> is an empty string, set <var>attrNs</var> to <var>elementNs</var>’s value.</p>
+        <p>If <var>attrNs</var> is an empty string, set <var>attrNs</var> to null.</p>
        <li data-md>
         <p>Let <var>interface</var> be the <a data-link-type="dfn" href="https://dom.spec.whatwg.org/#concept-element-interface" id="ref-for-concept-element-interface①">element interface</a> for <var>localName</var> and <var>elementNs</var>.</p>
        <li data-md>

spec/index.bs

@@ -538,7 +538,7 @@ initially empty.
     1. Set |localName| to |tagName| in [=ASCII lowercase=].
     1. Set |attribute| to |attribute| in [=ASCII lowercase=].
     1. If |elementNs| is an empty string, set |elementNs| to [=HTML namespace=].
-    1. If |attrNs| is an empty string, set |attrNs| to |elementNs|'s value.
+    1. If |attrNs| is an empty string, set |attrNs| to null.
     1. Let |interface| be the [=element interface=] for |localName| and |elementNs|.
     1. If |interface| does not have an IDL [=attribute=] that [=reflects=] a content attribute with
         |localName| [=attribute/local name=] and |attrNs| [=attribute/namespace=],