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._pages.map(pageView => {
      const viewport = pageView.pdfPage.getViewport({ scale: 1 });
      if (!this.enablePrintAutoRotate || isPortraitOrientation(viewport)) {
        return {
          width: viewport.width,
          height: viewport.height,
          rotation: viewport.rotation,
        };
      }
      
      return {
        width: viewport.height,
        height: viewport.width,
        rotation: (viewport.rotation - 90) % 360,
      };
    });
  }
  /**
   * @type {Promise<OptionalContentConfig | null>}
   */
  get optionalContentConfigPromise() {