Add "queue an element task" algorithm

This is a specialization of "queue a task", where the event loop and the
document are derived from the element.

This helps with #4980. For now only a couple instances were converted,
but the other 200+ will follow.

Author: dtapuska

source

@@ -27904,7 +27904,8 @@ was an English &lt;a href="/wiki/Music_hall">music hall&lt;/a> singer, ...</code
        pixel density</var>.</p></li>
 
        <li>
-        <p><span>Queue a task</span> to:</p>
+        <p><span>Queue an element task</span> on the <span>DOM manipulation task source</span>
+        given the <code>img</code> element and following steps:</p>
 
         <ol>
          <li><p>If <i>restart animation</i> is set, then <span>restart the
@@ -27954,12 +27955,20 @@ was an English &lt;a href="/wiki/Music_hall">music hall&lt;/a> singer, ...</code
      image request</span> for the <span>current request</span> and the <span>pending request</span>,
      and set <span>pending request</span> to null.</p></li>
 
-     <li><p>&#x231B; <span>Queue a task</span> to change the <span>current request</span>'s <span
-     data-x="img-req-url">current URL</span> to the empty string, and then, if the element has a
-     <code data-x="attr-img-src">src</code> attribute or it <span data-x="use srcset or
-     picture">uses <code>srcset</code> or <code>picture</code></span>, <span
-     data-x="concept-event-fire">fire an event</span> named <code data-x="event-error">error</code>
-     at the <code>img</code> element.</p></li>
+     <li>
+      <p>&#x231B; <span>Queue an element task</span> on the <span>DOM manipulation task
+      source</span> given the <code>img</code> element and the following steps:</p>
+
+      <ol>
+       <li><p>Change the <span>current request</span>'s <span data-x="img-req-url">current
+       URL</span> to the empty string.</p></li>
+
+       <li><p>If the element has a <code data-x="attr-img-src">src</code> attribute or it <span
+       data-x="use srcset or picture">uses <code>srcset</code> or <code>picture</code></span>, <span
+       data-x="concept-event-fire">fire an event</span> named <code
+       data-x="event-error">error</code> at the <code>img</code> element.</p></li>
+      </ol>
+     </li>
 
      <li><p>&#x231B; Return.</p></li>
     </ol>
@@ -91539,12 +91548,15 @@ dictionary <dfn>PromiseRejectionEventInit</dfn> : <span>EventInit</span> {
 
   <p>To <dfn data-export="">queue a task</dfn> on a <span>task source</span> <var>source</var>,
   which performs a series of steps <var>steps</var>, optionally given an event loop <var>event
-  loop</var>:</p>
+  loop</var> and a document <var>document</var>:</p>
 
   <ol>
    <li><p>If <var>event loop</var> was not given, set <var>event loop</var> to the <span>implied
    event loop</span>.</p></li>
 
+   <li><p>If <var>document</var> was not given, set <var>document</var> to the <span>implied
+   document</span>.</p></li>
+
    <li><p>Let <var>task</var> be a new <span data-x="concept-task">task</span>.</p></li>
 
    <li><p>Set <var>task</var>'s <span data-x="concept-task-steps">steps</span> to
@@ -91554,7 +91566,7 @@ dictionary <dfn>PromiseRejectionEventInit</dfn> : <span>EventInit</span> {
    <var>source</var>.</p></li>
 
    <li><p>Set <var>task</var>'s <span data-x="concept-task-document">document</span> to the
-   <span>implied document</span>.</p></li>
+   <var>document</var>.</p></li>
 
    <li><p>Set <var>task</var>'s <span>script evaluation environment settings object set</span> to an
    empty <span>set</span>.</p></li>
@@ -91565,13 +91577,32 @@ dictionary <dfn>PromiseRejectionEventInit</dfn> : <span>EventInit</span> {
    <li><p><span data-x="list append">Append</span> <var>task</var> to <var>queue</var>.</p></li>
   </ol>
 
+  <p>To <dfn data-export="">queue an element task</dfn> on a <span>task source</span>
+  <var>source</var>, with an element <var>element</var> and a series of steps
+  <var>steps</var>:</p>
+
+  <ol>
+   <li><p>Let <var>document</var> be <var>element</var>'s <span>node document</span>.</p></li>
+
+   <li><p>Let <var>event loop</var> be <var>document</var>'s <span
+   data-x="concept-relevant-realm">relevant realm</span>'s corresponding <span>agent</span>'s
+   <span>event loop</span>.</p></li>
+
+   <li><p><span>Queue a task</span> given <var>source</var>, <var>event loop</var>,
+   <var>document</var>, and <var>steps</var>.</p></li>
+  </ol>
+
   <p>To <dfn data-export="">queue a microtask</dfn> which performs a series of steps
-  <var>steps</var>, optionally given an event loop <var>event loop</var>:</p>
+  <var>steps</var>, optionally given an event loop <var>event loop</var> and a document
+  <var>document</var>:</p>
 
   <ol>
    <li><p>If <var>event loop</var> was not given, set <var>event loop</var> to the <span>implied
    event loop</span>.</p></li>
 
+   <li><p>If <var>document</var> was not given, set <var>document</var> to the <span>implied
+   document</span>.</p></li>
+
    <li><p>Let <var>microtask</var> be a new <span data-x="concept-task">task</span>.</p></li>
 
    <li><p>Set <var>microtask</var>'s <span data-x="concept-task-steps">steps</span> to
@@ -91580,8 +91611,8 @@ dictionary <dfn>PromiseRejectionEventInit</dfn> : <span>EventInit</span> {
    <li><p>Set <var>microtask</var>'s <span data-x="concept-task-source">source</span> to the
    <dfn>microtask task source</dfn>.</p></li>
 
-   <li><p>Set <var>microtask</var>'s <span data-x="concept-task-document">document</span> to the
-   <span>implied document</span>.</p></li>
+   <li><p>Set <var>microtask</var>'s <span data-x="concept-task-document">document</span> to
+   <var>document</var>.</p></li>
 
    <li><p>Set <var>task</var>'s <span>script evaluation environment settings object set</span> to an
    empty <span>set</span>.</p></li>