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.getDocJSActions();
  }
  /**
   * @typedef {Object} OutlineNode
   * @property {string} title
   * @property {boolean} bold
   * @property {boolean} italic
   * @property {Uint8ClampedArray} color - The color in RGB format to use for
   *   display purposes.
   * @property {string | Array<any> | null} dest
   * @property {string | null} url
   * @property {string | undefined} unsafeUrl
   * @property {boolean | undefined} newWindow
   * @property {number | undefined} count
   * @property {Array<OutlineNode>} items
   */
  /**
   * @returns {Promise<Array<OutlineNode>>} A promise that is resolved with an
   *   {Array} that is a tree outline (if it has one) of the PDF file.
   */
  getOutline() {