Revert "Add tentative enforcement for toggleAttribute"

This reverts commit 6e40964.

dom.bs

@@ -6918,17 +6918,11 @@ method steps are:
   <p>If <var>attribute</var> is null, then:
 
   <ol>
-   <li><p>Set <var>attribute</var> to an <a>attribute</a> whose
+   <li><p>If <var>force</var> is not given or is true, create an <a>attribute</a> whose
    <a for=Attr>local name</a> is <var>qualifiedName</var>, <a for=Attr>value</a> is the empty
-   string, and <a for=Node>node document</a> is <a>this</a>'s <a for=Node>node document</a>.
-
-   <li><p>Let <var>verifiedValue</var> be the result of calling <a>verify attribute value</a>
-   <var>attribute</var>'s <a for=Attr>value</a> for <var>attribute</var>, with <a>this</a>.
-
-   <li><p>Set <var>attribute</var>'s <a for=Attr>value</a> to <var>verifiedValue</var>.
-
-   <li><p>If <var>force</var> is not given or is true, then <a lt="append an attribute">append</a>
-   this <a>attribute</a> to <a>this</a>, and then return true.
+   string, and <a for=Node>node document</a> is <a>this</a>'s <a for=Node>node document</a>, then
+   <a lt="append an attribute">append</a> this <a>attribute</a> to <a>this</a>, and then return
+   true.
 
    <li><p>Return false.
   </ol>