Define the translate attribute's state when there's no parent element

Fixes whatwg#5239.

source

@@ -2986,6 +2986,7 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
      <li>The <dfn data-x-href="https://dom.spec.whatwg.org/#concept-tree-first-child">first child</dfn>,
              <dfn data-x-href="https://dom.spec.whatwg.org/#concept-tree-next-sibling">next sibling</dfn>, and
              <dfn data-x-href="https://dom.spec.whatwg.org/#concept-tree-previous-sibling">previous sibling</dfn> concepts</li>
+     <li>The <dfn data-x-href="https://dom.spec.whatwg.org/#parent-element">parent element</dfn> concept</li>
      <li>The <dfn data-x-href="https://dom.spec.whatwg.org/#document-element">document element</dfn> concept</li>
      <li>The <dfn data-x-href="https://dom.spec.whatwg.org/#in-a-document-tree">in a document tree</dfn>, <dfn data-x-href="https://dom.spec.whatwg.org/#in-a-document">in a document</dfn> (legacy), and <dfn data-x-href="https://dom.spec.whatwg.org/#connected">connected</dfn> concepts</li>
      <li>The <dfn data-x="concept-slot" data-x-href="https://dom.spec.whatwg.org/#concept-slot">slot</dfn> concept, and its <dfn data-x="slot-name" data-x-href="https://dom.spec.whatwg.org/#slot-name">name</dfn> and <dfn data-x-href="https://dom.spec.whatwg.org/#slot-assigned-nodes">assigned nodes</dfn></li>
@@ -12122,8 +12123,9 @@ Transport Protocol">HTTP&lt;/abbr> today.&lt;/p></code></pre> <!-- DO NOT REWRAP
   element's <code data-x="attr-translate">translate</code> attribute is in the <i>inherit</i> state,
   or the element is not an <span data-x="HTML elements">HTML element</span> and thus does not have a
   <code data-x="attr-translate">translate</code> attribute; in either case, the element's
-  <span>translation mode</span> is in the same state as its parent element's, if any, or in the
-  <span>translate-enabled</span> state, if the element is a <span>document element</span>.</p>
+  <span>translation mode</span> is in the same state as its <span>parent element</span>'s, if any,
+  or in the <span>translate-enabled</span> state, if the element's <span>parent element</span> is
+  null.</p>
 
   <p>When an element is in the <dfn>translate-enabled</dfn> state, the element's <span>translatable
   attributes</span> and the values of its <code>Text</code> node children are to be translated when