[web-animations-2] Fix markup

Author: fantasai

web-animations-2/Overview.bs

@@ -2896,6 +2896,7 @@ partial interface KeyframeEffect {
 ::  Amend the procedure to create a new {{KeyframeEffect}} object with the
     same properties as {{KeyframeEffect/KeyframeEffect(source)/source}} to include setting the
     <a>iteration composite operation</a> from <var>source</var> on <var>effect</var>.
+</div>
 
 <div class="attributes">
 :   <dfn attribute for=KeyframeEffect>iterationComposite</dfn>
@@ -2905,6 +2906,7 @@ partial interface KeyframeEffect {
 
     On setting, sets the <a>iteration composite operation</a> property of this
     <a>animation effect</a> to the provided value.
+</div>
 
 <h4 id="creating-a-new-keyframeeffect-object">Creating a new <code>KeyframeEffect</code> object</h4>