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 (!this._annotationsPromise || this._annotationsIntent !== intent) {
      this._annotationsPromise = this._transport.getAnnotations(
        this._pageIndex,
        intent
      );
      this._annotationsIntent = intent;
    }
    return this._annotationsPromise;
  }
  /**
   * @returns {Promise<Object>} A promise that is resolved with an
   *   {Object} with JS actions.
   */
  getJSActions() {