Method whenFirstPreviewedOrVisible

src/service/ampdoc-impl.js:664–666

* Returns a Promise that only ever resolved when the current * AMP document first reaches the `PREVIEW` visibility state. * @return {!Promise}

()

   * @return {!Promise}
   */
  whenFirstPreviewedOrVisible() {
    return Promise.race([this.whenFirstPreviewed(), this.whenFirstVisible()]);
  }

  /**
   * Returns a Promise that only ever resolved when the current