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)

if (!(promise instanceof Promise)) {
      throw new Error(`Invalid optionalContentConfigPromise: ${promise}`);
    }
    if (!this.pdfDocument) {
      return;
    }
    if (!this._optionalContentConfigPromise) {
      
      
      return;
    }
    this._optionalContentConfigPromise = promise;
    for (const pageView of this._pages) {
      pageView.update(pageView.scale, pageView.rotation, promise);
    }
    this.update();
    this.eventBus.dispatch("optionalcontentconfigchanged", {
      source: this,
      promise,
    });
  }
  /**
   * @type {number} One of the values in {ScrollMode}.
   */
  get scrollMode() {