diff --git a/source b/source
index abebcd5f3da..819d5b9ab3f 100644
--- a/source
+++ b/source
@@ -3366,8 +3366,7 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
 
      <li>The <dfn data-x="document's character encoding" data-x-href="https://dom.spec.whatwg.org/#concept-document-encoding">encoding</dfn> (herein the <i>character encoding</i>),
              <dfn data-x="concept-document-mode" data-x-href="https://dom.spec.whatwg.org/#concept-document-mode">mode</dfn>,
-             <dfn data-x="document-custom-element-registry" data-x-href="https://dom.spec.whatwg.org/#document-custom-element-registry">custom element registry</dfn>,
-             <dfn data-x="concept-document-allow-declarative-shadow-roots" data-x-href="https://dom.spec.whatwg.org/#concept-document-allow-declarative-shadow-roots">allow declarative shadow roots</dfn>, and
+             <dfn data-x="document-custom-element-registry" data-x-href="https://dom.spec.whatwg.org/#document-custom-element-registry">custom element registry</dfn>, and
              <dfn data-x="concept-document-content-type" data-x-href="https://dom.spec.whatwg.org/#concept-document-content-type">content type</dfn> of a <code>Document</code></li>
      <li>The distinction between <dfn data-x-href="https://dom.spec.whatwg.org/#xml-document">XML documents</dfn> and
                                  <dfn data-x-href="https://dom.spec.whatwg.org/#html-document">HTML documents</dfn></li>
@@ -104529,10 +104528,6 @@ interface <dfn interface>NotRestoredReasons</dfn> {
      <dt><span data-x="concept-document-about-base-URL">about base URL</span></dt>
      <dd><var>creatorBaseURL</var></dd>
 
-     <dt><span data-x="concept-document-allow-declarative-shadow-roots">allow declarative shadow
-     roots</span></dt>
-     <dd>true</dd>
-
      <dt><span data-x="document-custom-element-registry">custom element registry</span></dt>
      <dd>a new <code>CustomElementRegistry</code> object</dd>
     </dl>
@@ -111363,10 +111358,6 @@ location.href = '#foo';</code></pre>
      <dt><span data-x="concept-document-about-base-url">about base URL</span></dt>
      <dd><var>navigationParams</var>'s <span data-x="navigation-params-about-base-URL">about base URL</span></dd>
 
-     <dt><span data-x="concept-document-allow-declarative-shadow-roots">allow declarative shadow
-     roots</span></dt>
-     <dd>true</dd>
-
      <dt><span data-x="document-custom-element-registry">custom element registry</span></dt>
      <dd>a new <code>CustomElementRegistry</code> object</dd>
     </dl>
@@ -123879,10 +123870,6 @@ enum <dfn enum>DOMParserSupportedType</dfn> {
     is disabled</span>.</p>
    </li>
 
-   <li><p>Set <var>document</var>'s <span
-   data-x="concept-document-allow-declarative-shadow-roots">allow declarative shadow roots</span> to
-   true.</p></li>
-
    <li><p><span>Parse HTML from a string</span> given <var>document</var> and
    <var>compliantHTML</var>.</p></li>
 
@@ -136616,6 +136603,9 @@ dictionary <dfn dictionary>StorageEventInit</dfn> : <span>EventInit</span> {
   <p>The <dfn>frameset-ok flag</dfn> is set to "ok" when the parser is created. It is set to "not
   ok" after certain tokens are seen.</p>
 
+  <p>The <dfn>allow declarative shadow roots flag</dfn> can be enabled to support the
+  <code data-x="attr-template-shadowrootmode">shadowrootmode</code> attribute.</p>
+
   </div>
 
 
@@ -140296,9 +140286,7 @@ document.body.appendChild(text);
        data-x="attr-template-shadowrootmode">shadowrootmode</code> is not in the <span
        data-x="attr-shadowrootmode-none-state">None</span> state;</li>
 
-       <li><var>document</var>'s <span
-       data-x="concept-document-allow-declarative-shadow-roots">allow declarative shadow
-       roots</span> is true; or</li>
+       <li>the <span>allow declarative shadow roots flag</span> is enabled; or</li>
 
        <li>the <span>adjusted current node</span> is not the topmost element in the <span>stack of
        open elements</span>,</li>
@@ -144533,12 +144521,11 @@ console.assert(container.firstChild instanceof SuperP);
    document</span> is in <span>limited-quirks mode</span>, then set <var>document</var>'s <span
    data-x="concept-document-mode">mode</span> to "<code data-x="">limited-quirks</code>".</p></li>
 
-   <li><p>If <var>allowDeclarativeShadowRoots</var> is true, then set <var>document</var>'s <span
-   data-x="concept-document-allow-declarative-shadow-roots">allow declarative shadow roots</span> to
-   true.</p></li>
-
    <li><p>Create a new <span>HTML parser</span>, and associate it with <var>document</var>.</p></li>
 
+   <li><p>If <var>allowDeclarativeShadowRoots</var> is true, then set the <span>HTML parser</span>'s
+   <span>allow declarative shadow roots flag</span> to enabled.</p></li>
+
    <li>
     <p>Set the state of the <span>HTML parser</span>'s <span>tokenization</span> stage as
     follows, switching on the <var data-x="concept-frag-parse-context">context</var> element:</p>