Scope non-scoped (global) registries to a single document

This preserves existing behavior. We throw exceptions in certain corner cases to give us some wiggle room in the future.

Corresponding HTML PR: whatwg/html#11472.

Tests: web-platform-tests/wpt#53791.

Fixes #1390.

Author: annevk

dom.bs

@@ -4854,6 +4854,10 @@ and an optional <a for=/>document</a> <dfn export for="clone a node"><var>docume
    <li><p>Let <var>shadowRootRegistry</var> be <var>node</var>'s <a for=Element>shadow root</a>'s
    <a for=ShadowRoot>custom element registry</a>.
 
+   <li><p>If <var>shadowRootRegistry</var> <a>is a global custom element registry</a>, then set
+   <var>shadowRootRegistry</var> to <var>document</var>'s
+   <a>effective global custom element registry</a>.
+
    <li><p><a>Attach a shadow root</a> with <var>copy</var>, <var>node</var>'s
    <a for=Element>shadow root</a>'s <a for=ShadowRoot>mode</a>, true, <var>node</var>'s
    <a for=Element>shadow root</a>'s <a for=ShadowRoot>serializable</a>, <var>node</var>'s
@@ -4896,6 +4900,9 @@ and an optional <a for=/>document</a> <dfn export for="clone a node"><var>docume
    <li><p>If <var>registry</var> is null, then set <var>registry</var> to
    <var>fallbackRegistry</var>.
 
+   <li><p>If <var>registry</var> <a>is a global custom element registry</a>, then set
+   <var>registry</var> to <var>document</var>'s <a>effective global custom element registry</a>.
+
    <li><p>Set <var>copy</var> to the result of <a>creating an element</a>, given
    <var>document</var>, <var>node</var>'s <a for=Element>local name</a>, <var>node</var>'s
    <a for=Element>namespace</a>, <var>node</var>'s <a for=Element>namespace prefix</a>,
@@ -4920,10 +4927,18 @@ and an optional <a for=/>document</a> <dfn export for="clone a node"><var>docume
 
   <dl class=switch>
    <dt>{{Document}}
-   <dd><p>Set <var>copy</var>'s <a for=Document>encoding</a>, <a for=Document>content type</a>,
-   <a for=Document>URL</a>, <a for=Document>origin</a>, <a for=Document>type</a>,
-   <a for=Document>mode</a>, <a for=Document>allow declarative shadow roots</a>, and
-   <a for=Document>custom element registry</a> to those of <var>node</var>.
+   <dd>
+    <ol>
+     <li><p>Set <var>copy</var>'s <a for=Document>encoding</a>, <a for=Document>content type</a>,
+     <a for=Document>URL</a>, <a for=Document>origin</a>, <a for=Document>type</a>,
+     <a for=Document>mode</a>, and <a for=Document>allow declarative shadow roots</a>, to those of
+     <var>node</var>.
+
+     <li><p>If <var>node</var>'s <a for=Document>custom element registry</a>'s
+     <a for=CustomElementRegistry>is scoped</a> is true, then set <var>copy</var>'s
+     <a for=Document>custom element registry</a> to <var>node</var>'s
+     <a for=Document>custom element registry</a>.
+    </ol>
 
    <dt>{{DocumentType}}
    <dd><p>Set <var>copy</var>'s <a for=DocumentType>name</a>, <a>public ID</a>, and
@@ -5774,6 +5789,7 @@ method steps are to return the <a>list of elements with class names <var>classNa
 <p class=note>The HTML Standard will, e.g., define that for <code>html</code> and the
 <a>HTML namespace</a>, the {{HTMLHtmlElement}} interface is used. [[!HTML]]
 
+<div algorithm>
 <p>The
 <dfn method for=Document><code>createElement(<var>localName</var>, <var>options</var>)</code></dfn>
 method steps are:
@@ -5795,7 +5811,9 @@ method steps are:
  <li><p>Return the result of <a>creating an element</a> given <a>this</a>, <var>localName</var>,
  <var>namespace</var>, null, <var>is</var>, true, and <var>registry</var>.
 </ol>
+</div>
 
+<div algorithm>
 <p>The <dfn noexport>internal <code>createElementNS</code> steps</dfn>, given <var>document</var>,
 <var>namespace</var>, <var>qualifiedName</var>, and <var>options</var>, are as follows:
 
@@ -5811,13 +5829,17 @@ method steps are:
  <var>localName</var>, <var>namespace</var>, <var>prefix</var>, <var>is</var>, true, and
  <var>registry</var>.
 </ol>
+</div>
 
+<div algorithm>
 <p>The
 <dfn method for=Document><code>createElementNS(<var>namespace</var>, <var>qualifiedName</var>, <var>options</var>)</code></dfn>
 method steps are to return the result of running the
 <a>internal <code>createElementNS</code> steps</a>, given <a>this</a>, <var>namespace</var>,
 <var>qualifiedName</var>, and <var>options</var>.
+</div>
 
+<div algorithm>
 <p>To <dfn>flatten element creation options</dfn>, given a string or {{ElementCreationOptions}}
 dictionary <var>options</var> and a <a for=/>document</a> <var>document</var>:
 
@@ -5833,6 +5855,10 @@ dictionary <var>options</var> and a <a for=/>document</a> <var>document</var>:
    <li><p>If <var>options</var>["{{ElementCreationOptions/customElementRegistry}}"]
    <a for=map>exists</a>, then set <var>registry</var> to it.
 
+   <li><p>If <var>registry</var>'s <a for=CustomElementRegistry>is scoped</a> is false and
+   <var>registry</var> is not <var>document</var>'s <a for=Document>custom element registry</a>,
+   then <a>throw</a> a "{{NotSupportedError!!exception}}" {{DOMException}}.
+
    <li><p>If <var>options</var>["{{ElementCreationOptions/is}}"] <a for=map>exists</a>, then set
    <var>is</var> to it.
 
@@ -5848,6 +5874,7 @@ dictionary <var>options</var> and a <a for=/>document</a> <var>document</var>:
 
 <p class=note>{{Document/createElement()}} and {{Document/createElementNS()}}'s <var>options</var>
 parameter is allowed to be a string for web compatibility.
+</div>
 
 <p>The <dfn method for=Document><code>createDocumentFragment()</code></dfn> method steps are to
 return a new {{DocumentFragment}} <a for=/>node</a> whose <a for=Node>node document</a> is
@@ -5944,6 +5971,10 @@ method steps are:
 
    <li><p>If <var>options</var>["{{ImportNodeOptions/customElementRegistry}}"]
    <a for=map>exists</a>, then set <var>registry</var> to it.
+
+   <li><p>If <var>registry</var>'s <a for=CustomElementRegistry>is scoped</a> is false and
+   <var>registry</var> is not <a>this</a>'s <a for=Document>custom element registry</a>, then
+   <a>throw</a> a "{{NotSupportedError!!exception}}" {{DOMException}}.
   </ol>
 
  <li><p>If <var>registry</var> is null, then set <var>registry</var> to the result of
@@ -5956,11 +5987,14 @@ method steps are:
 </ol>
 </div>
 
+<div algorithm>
 <p><a lt="Other applicable specifications">Specifications</a> may define
 <dfn export id=concept-node-adopt-ext>adopting steps</dfn> for all or some <a for=/>nodes</a>. The
-algorithm is passed <var>node</var> and <var>oldDocument</var>, as indicated in the <a>adopt</a>
-algorithm.
+algorithm is passed <var ignore>node</var> and <var ignore>oldDocument</var>, as indicated in the
+<a>adopt</a> algorithm.
+</div>
 
+<div algorithm>
 <p>To <dfn export id=concept-node-adopt>adopt</dfn> a <var>node</var> into a <var>document</var>, run
 these steps:
 
@@ -5981,9 +6015,24 @@ these steps:
     <ol>
      <li><p>Set <var>inclusiveDescendant</var>'s <a for=Node>node document</a> to <var>document</var>.
 
-     <li><p>If <var>inclusiveDescendant</var> is an <a for=/>element</a>, then set the
-     <a for=Node>node document</a> of each <a>attribute</a> in <var>inclusiveDescendant</var>'s
-     <a for=Element>attribute list</a> to <var>document</var>.
+     <li><p>If <var>inclusiveDescendant</var> is a <a for=/>shadow root</a> and
+     <var>inclusiveDescendant</var>'s <a for=ShadowRoot>custom element registry</a>
+     <a>is a global custom element registry</a>, then set <var>inclusiveDescendant</var>'s
+     <a for=ShadowRoot>custom element registry</a> to <var>document</var>'s
+     <a>effective global custom element registry</a>.
+
+     <li>
+      <p>Otherwise, if <var>inclusiveDescendant</var> is an <a for=/>element</a>:
+
+      <ol>
+       <li><p>Set the <a for=Node>node document</a> of each <a>attribute</a> in
+       <var>inclusiveDescendant</var>'s <a for=Element>attribute list</a> to <var>document</var>.
+
+       <li><p>If <var>inclusiveDescendant</var>'s <a for=Element>custom element registry</a>
+       <a>is a global custom element registry</a>, then set <var>inclusiveDescendant</var>'s
+       <a for=Element>custom element registry</a> to <var>document</var>'s
+       <a>effective global custom element registry</a>.
+      </ol>
     </ol>
 
    <li><p>For each <var>inclusiveDescendant</var> in <var>node</var>'s
@@ -5997,7 +6046,9 @@ these steps:
    <a>adopting steps</a> with <var>inclusiveDescendant</var> and <var>oldDocument</var>.
   </ol>
 </ol>
+</div>
 
+<div algorithm>
 <p>The <dfn method for=Document><code>adoptNode(<var>node</var>)</code></dfn> method steps are:
 
 <ol>
@@ -6014,6 +6065,24 @@ these steps:
 
  <li><p>Return <var>node</var>.
 </ol>
+</div>
+
+<hr>
+
+<p>Null or a {{CustomElementRegistry}} object <var>registry</var>
+<dfn>is a global custom element registry</dfn> if <var>registry</var> is non-null and
+<var>registry</var>'s <a for=CustomElementRegistry>is scoped</a> is false.</p>
+
+<p>A <a for=/>document</a> <var>document</var>'s <dfn>effective global custom element registry</dfn>
+is:
+
+<ol>
+ <li><p>If <var>document</var>'s <a for=Document>custom element registry</a>
+ <a>is a global custom element registry</a>, then return <var>document</var>'s
+ <a for=Document>custom element registry</a>.
+
+ <li><p>Return null.
+</ol>
 
 <hr>
 
@@ -7515,8 +7584,17 @@ are:
 <ol>
  <li><p>Let <var>registry</var> be <a>this</a>'s <a for=Element>custom element registry</a>.
 
- <li><p>If <var>init</var>["{{ShadowRootInit/customElementRegistry}}"] is non-null, then set
- <var>registry</var> to it.
+ <li>
+  <p>If <var>init</var>["{{ShadowRootInit/customElementRegistry}}"] is non-null:
+
+  <ol>
+   <li><p>Set <var>registry</var> to <var>init</var>["{{ShadowRootInit/customElementRegistry}}"].
+
+   <li><p>If <var>registry</var>'s <a for=CustomElementRegistry>is scoped</a> is false and
+   <var>registry</var> is not <a>this</a>'s <a>node document</a>'s
+   <a for=Document>custom element registry</a>, then <a>throw</a> a
+   "{{NotSupportedError!!exception}}" {{DOMException}}.
+  </ol>
 
  <li><p>Run <a>attach a shadow root</a> with <a>this</a>,
  <var>init</var>["{{ShadowRootInit/mode}}"], <var>init</var>["{{ShadowRootInit/clonable}}"],