Most annotations, even unsupported ones, render just fine in PDF.js because of their appearance stream. However, there exist PDF files with annotations that do not have an appearance stream (even though this is a deprecated practice). In the latter case, PDF.js displays nothing. We need to have a fallback to a default appearance stream in that case, or create an appearance stream ourselves using the data present for the annotation (such as quad points and color). Below is a list of known PDF files that contain annotations without appearance streams, for which the types are listed.
- <s>http://pdfkit.org/docs/guide.pdf (Underline, Highlight and StrikeOut)</s>
- <s>http://www.plpdf.com/examples/PLPDF-SDK/Simple_Examples/37_Markup_annotation/markup.pdf (Underline, Highlight and StrikeOut)</s>
- <s>https://drive.google.com/file/d/0B6YhVF9p-y2AU0RlYjRKakFQRjQ/view?usp=sharing (Highlight, from #6382)</s>
- https://drive.google.com/open?id=0B6YhVF9p-y2Ad3VsWDRHRkRxY2c (FreeText, from #6246)
- https://drive.google.com/file/d/0B-_5BgJGB33Ea2dQZnpUY2FvYkk/view (FreeText, from #6564)
- http://mirrors.rit.edu/CTAN/macros/latex/contrib/pdfcomment/doc/example.pdf (practically all annotation types, from #1973)

if (
      (typeof PDFJSDev === "undefined" ||
        PDFJSDev.test("!PRODUCTION || TESTING")) &&
      this.appearance &&
      !this._streams.includes(this.appearance)
    ) {
      unreachable("The appearance stream should always be reset.");
    }
    for (const stream of this._streams) {
      stream.reset();
    }
  }
  /**
   * Construct the (fully qualified) field name from the (partial) field
   * names of the field and its ancestors.
   *
   * @private
   * @memberof Annotation
   * @param {Dict} dict - Complete widget annotation dictionary
   * @returns {string}
   */
  _constructFieldName(dict) {