loadScriptSrc(url) {
    const newScript = _a.doc.createElement("script");
    newScript.src = url;
    newScript.async = false;
    _a.doc.head.appendChild(newScript);
  }
Attach a new remote script to the end of HEAD synchronously
NOTE: It takes too long for most scripts to finish loading
      so this is pretty useless to work with the dynamic UI features directly.
@param {string} url The url to be used in the script src attribute