Viewer:  https://mozilla.github.io/pdf.js/web/viewer.html
Chrome on Windows 10
When the attached PDF file is viewed, some of the fonts display as garbled text. 
[Arial, Courier, Times New Roman]
The file views correctly in Adobe Reader.
[fff.pdf](https://github.com/mozilla/pdf.js/files/4652174/fff.pdf)

const renderer = FontRendererFactory.create(this, SEAC_ANALYSIS_ENABLED);
    return shadow(this, "renderer", renderer);
  }
  exportData(extraProperties = false) {
    const exportDataProperties = extraProperties
      ? [...EXPORT_DATA_PROPERTIES, ...EXPORT_DATA_EXTRA_PROPERTIES]
      : EXPORT_DATA_PROPERTIES;
    const data = Object.create(null);
    let property, value;
    for (property of exportDataProperties) {
      value = this[property];
      
      if (value !== undefined) {
        data[property] = value;
      }
    }
    return data;
  }
  fallbackToSystemFont(properties) {