State-preserving atomic move integration

source

@@ -3218,6 +3218,7 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
      <li><dfn data-x="dom-Node-append" data-x-href="https://dom.spec.whatwg.org/#dom-node-append"><code>append()</code></dfn> method</li>
      <li><dfn data-x="dom-Node-appendChild" data-x-href="https://dom.spec.whatwg.org/#dom-node-appendchild"><code>appendChild()</code></dfn> method</li>
      <li><dfn data-x="dom-Node-cloneNode" data-x-href="https://dom.spec.whatwg.org/#dom-node-clonenode"><code>cloneNode()</code></dfn> method</li>
+     <li><dfn data-x="dom-Node-moveBefore" data-x-href="https://dom.spec.whatwg.org/#dom-node-moveBefore"><code>moveBefore()</code></dfn> method</li>
      <li><dfn data-x="dom-Document-importNode" data-x-href="https://dom.spec.whatwg.org/#dom-document-importnode"><code>importNode()</code></dfn> method</li>
      <li><dfn data-x="dom-Event-preventDefault" data-x-href="https://dom.spec.whatwg.org/#dom-event-preventdefault"><code>preventDefault()</code></dfn> method</li>
      <li><dfn data-x="dom-Element-id" data-x-href="https://dom.spec.whatwg.org/#dom-element-id"><code>id</code></dfn> attribute</li>
@@ -10820,6 +10821,17 @@ partial interface <dfn id="document" data-lt="">Document</dfn> {
   <span>set</span> of <span data-x="nrr-details-struct">not restored reason details</span>,
   initially empty.</p>
 
+  <p>Each <code>Document</code> has a <dfn
+  data-x="concept-document-state-preserving-atomic-move-in-progress" export
+  for="Document">state-preserving atomic move in progress</dfn> boolean, which is initially
+  false.</p>
+
+  <p class="note">This is set by <code data-x="dom-Node-moveBefore">moveBefore()</code> when a
+  <code>Document</code> is performing a state-preserving atomic move; it is used to exempt certain
+  <span data-x="concept-node-insert-ext">insertion steps</span> and <span
+  data-x="concept-node-remove-ext">removing steps</span> (and their kin), from running, if they
+  would ordinarily reset state that needs to be preserved.</p>
+
   <h4>The <code>DocumentOrShadowRoot</code> interface</h4>
 
   <p><cite>DOM</cite> defines the <code data-x="DOM
@@ -29024,6 +29036,10 @@ interface <dfn interface>HTMLSourceElement</dfn> : <span>HTMLElement</span> {
   steps</span>, given <var>insertedNode</var>, are:</p>
 
   <ol>
+   <li><p>If <var>insertedNode</var>'s <span>node document</span>'s <span
+   data-x="concept-document-state-preserving-atomic-move-in-progress">state-preserving atomic move
+   in progress</span> is true, then return.</p></li>
+
    <li><p>If <var>insertedNode</var>'s parent is a <span>media element</span> that has no <code
    data-x="attr-media-src">src</code> attribute and whose <code
    data-x="dom-media-networkState">networkState</code> has the value <code
@@ -29040,6 +29056,10 @@ interface <dfn interface>HTMLSourceElement</dfn> : <span>HTMLElement</span> {
   steps</span>, given <var>removedNode</var> and <var>oldParent</var>, are:</p>
 
   <ol>
+   <li><p>If <var>insertedNode</var>'s <span>node document</span>'s <span
+   data-x="concept-document-state-preserving-atomic-move-in-progress">state-preserving atomic move
+   in progress</span> is true, then return.</p></li>
+
    <li><p>If <var>removedNode</var>'s next sibling was an <code>img</code> element and
    <var>oldParent</var> is a <code>picture</code> element, then, count this as a <span
    data-x="relevant mutations">relevant mutation</span> for the <code>img</code> element.</p></li>
@@ -29301,6 +29321,10 @@ interface <dfn interface>HTMLImageElement</dfn> : <span>HTMLElement</span> {
   steps</span>, given <var>insertedNode</var>, are:</p>
 
   <ol>
+   <li><p>If <var>insertedNode</var>'s <span>node document</span>'s <span
+   data-x="concept-document-state-preserving-atomic-move-in-progress">state-preserving atomic move
+   in progress</span> is true, then return.</p></li>
+
    <li><p>If <var>insertedNode</var>'s parent is a <code>picture</code> element, then, count this as
    a <span data-x="relevant mutations">relevant mutation</span> for
    <var>insertedNode</var>.</p></li>
@@ -29310,6 +29334,10 @@ interface <dfn interface>HTMLImageElement</dfn> : <span>HTMLElement</span> {
   steps</span>, given <var>removedNode</var> and <var>oldParent</var>, are:</p>
 
   <ol>
+   <li><p>If <var>insertedNode</var>'s <span>node document</span>'s <span
+   data-x="concept-document-state-preserving-atomic-move-in-progress">state-preserving atomic move
+   in progress</span> is true, then return.</p></li>
+
    <li><p>If <var>oldParent</var> is a <code>picture</code> element, then, count this as a
    <span data-x="relevant mutations">relevant mutation</span> for <var>removedNode</var>.</p></li>
   </ol>
@@ -30809,7 +30837,9 @@ was an English &lt;a href="/wiki/Music_hall">music hall&lt;/a> singer, ...</code
 
    <li><p>The <code>img</code> or <code>source</code> <span>HTML element insertion steps</span> or
    <span>HTML element removing steps</span> count the mutation as a <span data-x="relevant
-   mutations">relevant mutation</span>.</p></li>
+   mutations">relevant mutation</span>, when the element's <span>node document</span>'s <span
+   data-x="concept-document-state-preserving-atomic-move-in-progress">state-preserving atomic move
+   in progress</span> is false.</p></li>
 
    <li><p>The element's parent is a <code>picture</code> element and a <code>source</code> element
    that is a previous sibling has its <code data-x="attr-source-srcset">srcset</code>, <code
@@ -33281,6 +33311,10 @@ interface <dfn interface>HTMLIFrameElement</dfn> : <span>HTMLElement</span> {
   <var>insertedNode</var>, are:</p>
 
   <ol>
+   <li><p>If <var>insertedNode</var>'s <span>node document</span>'s <span
+   data-x="concept-document-state-preserving-atomic-move-in-progress">state-preserving atomic move
+   in progress</span> is true, then return.</p></li>
+
    <li><p>If <var>insertedNode</var>'s <span>shadow-including root</span>'s <span
    data-x="concept-document-bc">browsing context</span> is null, then return.</p></li>
 
@@ -33296,8 +33330,15 @@ interface <dfn interface>HTMLIFrameElement</dfn> : <span>HTMLElement</span> {
   </ol>
 
   <p>The <code>iframe</code> <span>HTML element removing steps</span>, given
-  <var>removedNode</var>, are to <span>destroy a child navigable</span> given
-  <var>removedNode</var>.</p>
+  <var>removedNode</var>, are:</p>
+
+  <ol>
+   <li><p>If <var>insertedNode</var>'s <span>node document</span>'s <span
+   data-x="concept-document-state-preserving-atomic-move-in-progress">state-preserving atomic move
+   in progress</span> is true, then return.</p></li>
+
+   <li><p><span>Destroy a child navigable</span> given <var>removedNode</var>.</p>
+  </ol>
 
   <p class="note">This happens without any <code data-x="event-unload">unload</code> events firing
   (the element's <span>content document</span> is <em><span data-x="destroy a child