Editorial: fix typo in custom elements section

source

@@ -72891,7 +72891,7 @@ customElements.define("x-foo", class extends HTMLElement {
  data-x="custom-element-upgrades">upgrades</span> as well.)</p>
 
  <p>Each <span>custom element reactions stack</span> has an associated <dfn>backup element
- queue</dfn>, which an initially-empty <span>element queue</span>. Elements are pushed onto the
+ queue</dfn>, which is an initially-empty <span>element queue</span>. Elements are pushed onto the
  <span>backup element queue</span> during operations that affect the DOM without going through an
  API decorated with <code data-x="CEReactions">[CEReactions]</code>, or through the parser's
  <span>create an element for the token</span> algorithm. An example of this is a user-initiated