From e64379717b934682d7d7fd6be3f971ec9fa348ed Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philip=20J=C3=A4genstedt?= <philip@foolip.org>
Date: Mon, 22 May 2017 15:10:50 +0200
Subject: [PATCH 1/4] Reinstate the hierarchy restrictions

This reinstates parts of the fullscreen element ready check removed in
commit 766dc872bcf26c012549f7bdfde21c46bebba40c and
commit 9592913bbeca3a9d029274f310eb27ad8003622c, with some
simplification of the iframe ancestor check.
---
 fullscreen.bs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fullscreen.bs b/fullscreen.bs
index bd54a2c..12fb3c5 100644
--- a/fullscreen.bs
+++ b/fullscreen.bs
@@ -182,6 +182,12 @@ if all of the following are true, and false otherwise:
 <ul>
  <li><p><var>element</var> is <a>connected</a>.
 
+ <li><p><var>element</var>'s <a>node document</a>'s <a>fullscreen element</a> is null, or is an
+ <a>inclusive ancestor</a> of <var>element</var>.
+ <!-- If /element/ is the fullscreen element, nothing happens -->
+
+ <li><p><var>element</var> has no <a>ancestor</a> <{iframe}> <a>element</a>.
+
  <li><p><var>element</var>'s <a>node document</a> is <a>allowed to use</a> the feature indicated by
  attribute name <code>allowfullscreen</code>.
  <!-- cross-process, recursive -->

From 44b0c10d02e109732253ddb9b97190273f3dba58 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philip=20J=C3=A4genstedt?= <philip@foolip.org>
Date: Tue, 23 May 2017 11:28:31 +0200
Subject: [PATCH 2/4] Add back recursive ready check from
 https://github.com/whatwg/fullscreen/pull/52

---
 fullscreen.bs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fullscreen.bs b/fullscreen.bs
index 12fb3c5..d4f9f1f 100644
--- a/fullscreen.bs
+++ b/fullscreen.bs
@@ -191,6 +191,11 @@ if all of the following are true, and false otherwise:
  <li><p><var>element</var>'s <a>node document</a> is <a>allowed to use</a> the feature indicated by
  attribute name <code>allowfullscreen</code>.
  <!-- cross-process, recursive -->
+
+ <li><p><var>element</var>'s <a>node document</a>'s <a>browsing context</a> either has a
+ <a>browsing context container</a> and the <a>fullscreen element ready check</a> returns true for
+ that <a>browsing context container</a>, or it has no <a>browsing context container</a>.
+ <!-- cross-process, recursive -->
 </ul>
 
 <p>The <dfn method for=Element><code>requestFullscreen()</code></dfn> method, when invoked, must run

From 81465e97c2399e916460f2b1b6ff678ebaf86102 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philip=20J=C3=A4genstedt?= <philip@foolip.org>
Date: Tue, 23 May 2017 11:31:42 +0200
Subject: [PATCH 3/4] Make dialog.requestFullscreen() an error

---
 fullscreen.bs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fullscreen.bs b/fullscreen.bs
index d4f9f1f..714b918 100644
--- a/fullscreen.bs
+++ b/fullscreen.bs
@@ -223,6 +223,8 @@ these steps:
    <a href=https://www.w3.org/Math/draft-spec/chapter2.html#interf.toplevel>MathML <code>math</code></a>
    element. [[!SVG]] [[!MATHML]]
 
+   <li><p><var>pending</var> is not a <{dialog}> <a>element</a>.
+
    <li><p>The <a>fullscreen element ready check</a> for <var>pending</var> returns true.
 
    <li><p><a>Fullscreen is supported</a>.

From fb22071e466c83884d46c71b14d8a0ffcbd4f82f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philip=20J=C3=A4genstedt?= <philip@foolip.org>
Date: Wed, 24 May 2017 11:19:03 +0200
Subject: [PATCH 4/4] In #top-layer-add, assert that the element isn't already
 present

---
 fullscreen.bs | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/fullscreen.bs b/fullscreen.bs
index 714b918..2b4359c 100644
--- a/fullscreen.bs
+++ b/fullscreen.bs
@@ -532,12 +532,14 @@ following characteristics:
  <code>right</code>, and <code>top</code> is zero.
 </ul>
 
-<p>To <dfn export for="top layer">add</dfn> an <var>element</var> to a <var>top layer</var>,
-<a for=set>remove</a> it from <var>top layer</var> and then <a for=set>append</a> it to
-<var>top layer</var>.
+<p>To <dfn export for="top layer">add</dfn> an <var>element</var> to a <var>top layer</var>, run
+these steps:
+
+<ol>
+ <li><p>Assert: <var>top layer</var> does not <a for=set>contain</a> <var>element</var>.
 
-<p class=note>In other words, <var>element</var> is moved to the end of <var>top layer</var> if it
-is already present.
+ <li><p><a for=set>Append</a> <var>element</var> to <var>top layer</var>.
+</ol>
 
 
 <h3 id=::backdrop-pseudo-element><code>::backdrop</code> pseudo-element</h3>