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 (isNaN(val)) {
      throw new Error("Invalid numeric scale.");
    }
    if (!this.pdfDocument) {
      return;
    }
    this._setScale(val, false);
  }
  /**
   * @type {string}
   */
  get currentScaleValue() {
    return this._currentScaleValue;
  }
  /**
   * @param val - The scale of the pages (in percent or predefined value).
   */
  set currentScaleValue(val) {
    if (!this.pdfDocument) {
      return;
    }
    this._setScale(val, false);
  }
  /**
   * @type {number}
   */
  get pagesRotation() {