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)

const currentPageNumber = this._currentPageNumber,
      pagesCount = this.pagesCount;
    if (currentPageNumber >= pagesCount) {
      return false;
    }
    const advance =
      this._getPageAdvance(currentPageNumber,  false) || 1;
    this.currentPageNumber = Math.min(currentPageNumber + advance, pagesCount);
    return true;
  }
  /**
   * Go to the previous page, taking scroll/spread-modes into account.
   * @returns {boolean} Whether navigation occured.
   */
  previousPage() {
    const currentPageNumber = this._currentPageNumber;
    if (currentPageNumber <= 1) {
      return false;
    }
    const advance =
      this._getPageAdvance(currentPageNumber,  true) || 1;
    this.currentPageNumber = Math.max(currentPageNumber - advance, 1);
    return true;
  }
}
export { BaseViewer };