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 visiblePages = currentlyVisiblePages || this._getVisiblePages();
    const scrollAhead = this._isScrollModeHorizontal
      ? this.scroll.right
      : this.scroll.down;
    const pageView = this.renderingQueue.getHighestPriority(
      visiblePages,
      this._pages,
      scrollAhead
    );
    if (pageView) {
      this._ensurePdfPageLoaded(pageView).then(() => {
        this.renderingQueue.renderView(pageView);
      });
      return true;
    }
    return false;
  }
  /**
   * @param {HTMLDivElement} textLayerDiv
   * @param {number} pageIndex
   * @param {PageViewport} viewport
   * @param {boolean} enhanceTextSelection
   * @param {EventBus} eventBus
   * @returns {TextLayerBuilder}
   */
  createTextLayerBuilder(