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)

}
      for (const internalRenderTask of intentState.renderTasks) {
        waitOn.push(internalRenderTask.completed);
        internalRenderTask.cancel();
      }
    }
    this.objs.clear();
    this._annotationsPromise = null;
    this._jsActionsPromise = null;
    this._xfaPromise = null;
    this._structTreePromise = null;
    this.pendingCleanup = false;
    return Promise.all(waitOn);
  }
  /**
   * Cleans up resources allocated by the page.
   *
   * @param {boolean} [resetStats] - Reset page stats, if enabled.
   *   The default value is `false`.
   * @returns {boolean} Indicates if clean-up was successfully run.
   */
  cleanup(resetStats = false) {
    this.pendingCleanup = true;
    return this._tryCleanup(resetStats);
  }
  /**
   * Attempts to clean up if rendering is in a state where that's possible.
   * @private
   */
  _tryCleanup(resetStats = false) {