Update set an attribute to verify attribute value as first step

dom.bs

@@ -6651,6 +6651,9 @@ string <var>namespace</var> (default null):</p>
 <a for=/>attribute</a> <var>attr</var> and an <a for=/>element</a> <var>element</var>:
 
 <ol>
+ <li><p>Let <var>verifiedValue</var> be the result of calling <a>verify attribute value</a>
+ <var>attr</var>'s <a for=Attr>value</a> for <var>attr</var>, with <var>element</var>.
+
  <li><p>If <var>attr</var>'s <a for=Attr>element</a> is neither null nor <var>element</var>,
  <a>throw</a> an "{{InUseAttributeError!!exception}}" {{DOMException}}.
 
@@ -6661,19 +6664,13 @@ string <var>namespace</var> (default null):</p>
 
  <li><p>If <var>oldAttr</var> is <var>attr</var>, return <var>attr</var>.
 
- <li><p>Let <var>verifiedValue</var> be the result of calling <a>verify attribute value</a>
- <var>attr</var>'s <a for=Attr>value</a> for <var>attr</var>, with <var>element</var>.
-
- <li><p>Set <var>attr</var>'s <a for=Attr>value</a> to <var>verifiedValue</var>.
-
- <li><p>If <var>attr</var>'s <a for=Attr>element</a> is neither null nor <var>element</var>,
- <a>throw</a> an "{{InUseAttributeError!!exception}}" {{DOMException}}.
-
  <li><p>If <var>oldAttr</var> is non-null, then <a lt="replace an attribute">replace</a>
  <var>oldAttr</var> with <var>attr</var>.
 
  <li><p>Otherwise, <a lt="append an attribute">append</a> <var>attr</var> to <var>element</var>.
 
+ <li><p>Set <var>attr</var>'s <a for=Attr>value</a> to <var>verifiedValue</var>.
+
  <li><p>Return <var>oldAttr</var>.
 </ol>
 </div>