Correct upgrade an element after Scoped Custom Element Registries

In an earlier design the active custom element constructor map was kept on the global. Unfortunately the change to agent wasn't applied everywhere.

Fixes #11223.

Author: annevk

source

@@ -74262,11 +74262,9 @@ customElements.define("x-foo", class extends HTMLElement {
    <li><p>Let <var>C</var> be <var>definition</var>'s <span
    data-x="concept-custom-element-definition-constructor">constructor</span>.</p></li>
 
-   <li><p>Let <var>registry</var> be <var>element</var>'s <span
-   data-x="element-custom-element-registry">custom element registry</span>.</p></li>
-
    <li><p><span data-x="map set">Set</span> the <span>surrounding agent</span>'s <span>active custom
-   element constructor map</span>[<var>C</var>] to <var>registry</var>.</p></li>
+   element constructor map</span>[<var>C</var>] to <var>element</var>'s <span
+   data-x="element-custom-element-registry">custom element registry</span>.</p></li>
 
    <li>
     <p>Run the following steps while catching any exceptions:</p>
@@ -74316,8 +74314,8 @@ customElements.define("x-foo", class extends HTMLElement {
 
     <ol>
      <li>
-      <p><span data-x="map remove">Remove</span> <var>registry</var>'s <span>relevant global
-      object</span>'s <span>active custom element constructor map</span>[<var>C</var>].</p>
+      <p><span data-x="map remove">Remove</span> the <span>surrounding agent</span>'s <span>active
+      custom element constructor map</span>[<var>C</var>].</p>
 
       <p class="note">This is a no-op if <var>C</var> immediately calls <code
       data-x="">super()</code> as it ought to do.</p>