code: function doctypeInInitialMode(p, token) {
      p._setDocumentType(token);
  
      if (token.forceQuirks || Doctype.isQuirks(token.name, token.publicId, token.systemId))
          p.treeAdapter.setQuirksMode(p.document);
  
      p.insertionMode = BEFORE_HTML_MODE;
  }
docs: 12.2.5.4.1 The "initial" insertion mode ------------------------------------------------------------------