unction _HTMLDocument() { return new DOMParser().parseFromString("<html></html>", "text/html"); },
        {},
        "text/html;charset=UTF-8",
        'HTML Document request has correct default Content-Type of "text/html;charset=UTF-8"'
      )
      request(
        function _HTMLDocument() { return new DOMParser().parseFromString("<html></html>", "text/html"); },
        {"Content-Type": "text/html+junk;charset=ASCII"},
        "text/html+junk;charset=UTF-8",
        "HTML Document request keeps setReq