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.getStats();
  }
  /**
   * Cleans up resources allocated by the document on both the main and worker
   * threads.
   *
   * NOTE: Do not, under any circumstances, call this method when rendering is
   * currently ongoing since that may lead to rendering errors.
   *
   * @param {boolean} [keepLoadedFonts] - Let fonts remain attached to the DOM.
   *   NOTE: This will increase persistent memory usage, hence don't use this
   *   option unless absolutely necessary. The default value is `false`.
   * @returns {Promise} A promise that is resolved when clean-up has finished.
   */
  cleanup(keepLoadedFonts = false) {