Remove registry restoration on insert but do it in adopt

Author: Jayson Chen

dom.bs

@@ -2902,12 +2902,7 @@ before a <var>child</var>, with an optional <i>suppress observers flag</i>, run
       <p>If <var>inclusiveDescendant</var> is an <a for=/>element</a>:
 
       <ol>
-       <li><p>If <var>inclusiveDescendant</var>'s <a for=Element>custom element registry</a> is
-       null, then set <var>inclusiveDescendant</var>'s <a for=Element>custom element registry</a> to
-       the result of <a for=/>looking up a custom element registry</a> given
-       <var>inclusiveDescendant</var>'s <a for=tree>parent</a>.
-
-       <li><p>Otherwise, if <var>inclusiveDescendant</var>'s
+       <li><p>If <var>inclusiveDescendant</var>'s
        <a for=Element>custom element registry</a>'s <a for=CustomElementRegistry>is scoped</a> is
        true, <a for=set>append</a> <var>inclusiveDescendant</var>'s <a for=Node>node document</a> to
        <var>inclusiveDescendant</var>'s <a for=Element>custom element registry</a>'s
@@ -2930,14 +2925,7 @@ before a <var>child</var>, with an optional <i>suppress observers flag</i>, run
       <p>Otherwise, if <var>inclusiveDescendant</var> is a <a for=/>shadow root</a>:
 
       <ol>
-       <li><p>If <var>inclusiveDescendant</var>'s <a for=ShadowRoot>custom element registry</a> is
-       null and <var>inclusiveDescendant</var>'s
-       <a for=ShadowRoot>keep custom element registry null</a> is false, then set
-       <var>inclusiveDescendant</var>'s <a for=ShadowRoot>custom element registry</a> to the result
-       of <a for=/>looking up a custom element registry</a> given <var>inclusiveDescendant</var>'s
-       <a for=DocumentFragment>host</a>.
-
-       <li><p>Otherwise, if <var>inclusiveDescendant</var>'s
+       <li><p>If <var>inclusiveDescendant</var>'s
        <a for=ShadowRoot>custom element registry</a> is non-null and
        <var>inclusiveDescendant</var>'s <a for=ShadowRoot>custom element registry</a>'s
        <a for=CustomElementRegistry>is scoped</a> is true, <a for=set>append</a>
@@ -6018,12 +6006,14 @@ 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 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>If <var>inclusiveDescendant</var> is a <a for=/>shadow root</a>:
+      <ol>
+        <li>If <var>inclusiveDescendant</var>'s <a for=ShadowRoot>custom element registry</a>
+        <a>is a global custom element registry</a> or null, 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>.
+      </ol>
+     
      <li>
       <p>Otherwise, if <var>inclusiveDescendant</var> is an <a for=/>element</a>:
 
@@ -6032,7 +6022,7 @@ these steps:
        <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>is a global custom element registry</a> or null, 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>
@@ -11047,6 +11037,7 @@ James Graham,
 James Greene,
 James M Snell,
 James Robinson,
+Jayson Chen,
 Jeffrey Yasskin,
 Jens Lindström,
 Jeremy Davis<!-- jeremydavis519; GitHub -->,