From c85fb47b1b14490521bec65a4b718b7f25a1b98e Mon Sep 17 00:00:00 2001
From: Luke Warlow <lwarlow@igalia.com>
Date: Mon, 27 Jan 2025 20:28:20 +0000
Subject: [PATCH 1/2] Add attribute changed steps to dialog element

When the dialogs open attribute is removed:

1. Remove dialog from the document's open dialogs list.
2. Destroy and nullify dialog's close watcher

This also adds an assertion to the start of
'set the dialog close watcher' that dialog's close watcher is null.
---
 source | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/source b/source
index 213f90acbef..4861fae586c 100644
--- a/source
+++ b/source
@@ -62084,6 +62084,38 @@ interface <dfn interface>HTMLDialogElement</dfn> : <span>HTMLElement</span> {
    <var>removedNode</var>'s <span>node document</span>'s <span>open dialogs list</span>.</p></li>
   </ol>
 
+  <p>The following <span data-x="concept-element-attributes-change-ext">attribute change
+  steps</span>, given <var>element</var>, <var>localName</var>, <var>oldValue</var>,
+  <var>value</var>, and <var>namespace</var> are used for <code>dialog</code> elements:</p>
+
+  <ol>
+   <li><p>If <var>namespace</var> is not null, then return.</p></li>
+
+   <li><p>If <var>localName</var> is not <code data-x="attr-dialog-open">open</code>, then
+   return.</p></li>
+
+   <li><p>If <var>value</var> is null:</p>
+
+    <ol>
+     <li><p><span data-x="list remove">Remove</span> <var>element</var> from <var>element</var>'s
+     <span>node document</span>'s <span>open dialogs list</span>.</p></li>
+
+     <li>
+      <p>If <var>element</var>'s <span data-x="dialog-close-watcher">close watcher</span> is not
+      null, then:</p>
+
+      <ol>
+       <li><p><span data-x="close-watcher-destroy">Destroy</span> <var>element</var>'s <span
+       data-x="dialog-close-watcher">close watcher</span>.</p></li>
+
+       <li><p>Set <var>element</var>'s <span data-x="dialog-close-watcher">close watcher</span> to
+       null.</p></li>
+      </ol>
+     </li>
+    </ol>
+   </li>
+  </ol>
+
   <p>To <dfn>show a modal dialog</dfn> given a <code>dialog</code> element <var>subject</var>:</p>
 
   <ol>
@@ -62178,6 +62210,9 @@ interface <dfn interface>HTMLDialogElement</dfn> : <span>HTMLElement</span> {
   element <var>dialog</var>:</p>
 
   <ol>
+   <li><p><span>Assert</span>: <span>dialog</span>'s <span data-x="dialog-close-watcher">close
+   watcher</span> is null.</p></li>
+
    <li>
     <p>Set <var>dialog</var>'s <span data-x="dialog-close-watcher">close watcher</span> to the
     result of <span data-x="establish a close watcher">establishing a close watcher</span> given

From 376c837f99ab031b60096312fc930e346e335b61 Mon Sep 17 00:00:00 2001
From: Luke Warlow <lwarlow@igalia.com>
Date: Sun, 2 Feb 2025 22:33:27 +0000
Subject: [PATCH 2/2] Replace assert in set the dialog close watcher with an
 early return

---
 source | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/source b/source
index 4861fae586c..5079500bc10 100644
--- a/source
+++ b/source
@@ -62210,8 +62210,8 @@ interface <dfn interface>HTMLDialogElement</dfn> : <span>HTMLElement</span> {
   element <var>dialog</var>:</p>
 
   <ol>
-   <li><p><span>Assert</span>: <span>dialog</span>'s <span data-x="dialog-close-watcher">close
-   watcher</span> is null.</p></li>
+   <li><p>If <span>dialog</span>'s <span data-x="dialog-close-watcher">close watcher</span> is not
+   null, then return.</p></li>
 
    <li>
     <p>Set <var>dialog</var>'s <span data-x="dialog-close-watcher">close watcher</span> to the