Add scrollend content and IDL attributes

This supports the feature described in https://drafts.csswg.org/cssom-view/#scrolling.

source

@@ -3873,6 +3873,7 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
      <li><dfn data-x-href="https://drafts.csswg.org/cssom-view/#scroll-to-the-beginning-of-the-document">Scroll to the beginning of the document</dfn></li>
      <li>The <dfn data-x="event-resize" data-x-href="https://drafts.csswg.org/cssom-view/#eventdef-window-resize"><code>resize</code></dfn> event</li>
      <li>The <dfn data-x="event-scroll" data-x-href="https://drafts.csswg.org/cssom-view/#eventdef-document-scroll"><code>scroll</code></dfn> event</li>
+     <li>The <dfn data-x="event-scrollend" data-x-href="https://drafts.csswg.org/cssom-view/#eventdef-document-scrollend"><code>scrollend</code></dfn> event</li>
      <li><dfn data-x-href="https://drafts.csswg.org/cssom-view/#set-up-browsing-context-features">set up browsing context features</dfn></li>
     </ul>
 
@@ -12494,6 +12495,7 @@ https://software.hixie.ch/utilities/js/live-dom-viewer/?%3C%21DOCTYPE%20HTML%3E%
    <li><code data-x="handler-onreset">onreset</code></li>
    <li><code data-x="handler-onresize">onresize</code>*</li>
    <li><code data-x="handler-onscroll">onscroll</code>*</li>
+   <li><code data-x="handler-onscrollend">onscrollend</code>*</li>
    <li><code data-x="handler-onsecuritypolicyviolation">onsecuritypolicyviolation</code></li>
    <li><code data-x="handler-onseeked">onseeked</code></li>
    <li><code data-x="handler-onseeking">onseeking</code></li>
@@ -101243,6 +101245,7 @@ typedef <span>OnBeforeUnloadEventHandlerNonNull</span>? <dfn typedef>OnBeforeUnl
     <tr><td><dfn attribute for="GlobalEventHandlers"><code data-x="handler-onload">onload</code></dfn> <td> <code data-x="event-load">load</code>
     <tr><td><dfn attribute for="GlobalEventHandlers"><code data-x="handler-onresize">onresize</code></dfn> <td> <code data-x="event-resize">resize</code>
     <tr><td><dfn attribute for="GlobalEventHandlers"><code data-x="handler-onscroll">onscroll</code></dfn> <td> <code data-x="event-scroll">scroll</code>
+    <tr><td><dfn attribute for="GlobalEventHandlers"><code data-x="handler-onscrollend">onscrollend</code></dfn> <td> <code data-x="event-scrollend">scrollend</code>
   </table>
 
   <p>We call the <span>set</span> of the <span data-x="event handler name">names</span> of the
@@ -101385,6 +101388,7 @@ typedef <span>OnBeforeUnloadEventHandlerNonNull</span>? <dfn typedef>OnBeforeUnl
   attribute <span>EventHandler</span> <span data-x="handler-onreset">onreset</span>;
   attribute <span>EventHandler</span> <span data-x="handler-onresize">onresize</span>;
   attribute <span>EventHandler</span> <span data-x="handler-onscroll">onscroll</span>;
+  attribute <span>EventHandler</span> <span data-x="handler-onscrollend">onscrollend</span>;
   attribute <span>EventHandler</span> <span data-x="handler-onsecuritypolicyviolation">onsecuritypolicyviolation</span>;
   attribute <span>EventHandler</span> <span data-x="handler-onseeked">onseeked</span>;
   attribute <span>EventHandler</span> <span data-x="handler-onseeking">onseeking</span>;
@@ -130098,6 +130102,12 @@ interface <dfn interface>External</dfn> {
      <td> <code data-x="event-scroll">scroll</code> event handler
      <td> <span data-x="event handler content attributes">Event handler content attribute</span>
 
+    <tr>
+     <th id="ix-handler-onscrollend"> <code data-x="">onscrollend</code>
+     <td> <span data-x="handler-onscrollend">HTML elements</span>
+     <td> <code data-x="event-scrollend">scrollend</code> event handler
+     <td> <span data-x="event handler content attributes">Event handler content attribute</span>
+
     <tr>
      <th id="ix-handler-onsecuritypolicyviolation"> <code data-x="">onsecuritypolicyviolation</code>
      <td> <span data-x="handler-onsecuritypolicyviolation">HTML elements</span>