I was wondering if WebGL is considered stable enough to be enabled by default. It makes some PDFs render much faster and it has been off by default for a while now, so we have had quite some time to test it.

If we decide to enable WebGL by default, we should not forget to update https://github.com/mozilla/pdf.js/blob/master/extensions/chromium/preferences_schema.json#L39 as well.

/cc @yurydelendik 
/cc @Snuffleupagus (because IIRC you were testing WebGL too)

return this._transport.getData();
  }
  /**
   * @returns {Promise<{ length: number }>} A promise that is resolved when the
   *   document's data is loaded. It is resolved with an {Object} that contains
   *   the `length` property that indicates size of the PDF data in bytes.
   */
  getDownloadInfo() {
    return this._transport.downloadInfoCapability.promise;
  }
  /**
   * @typedef {Object} PDFDocumentStats
   * @property {Object<string, boolean>} streamTypes - Used stream types in the
   *   document (an item is set to true if specific stream ID was used in the
   *   document).
   * @property {Object<string, boolean>} fontTypes - Used font types in the
   *   document (an item is set to true if specific font ID was used in the
   *   document).
   */
  /**
   * @returns {Promise<PDFDocumentStats>} A promise this is resolved with
   *   current statistics about document structures (see
   *   {@link PDFDocumentStats}).
   */
  getStats() {