imageLoadListeners() {
    var images = this.document.querySelectorAll("img");
    var img;

    for (var i = 0; i < images.length; i++) {
      img = images[i];

      if (typeof img.naturalWidth !== "undefined" && img.naturalWidth === 0) {
        img.onload = this.expand.bind(this);
      }
    }
  }
Test if images are loaded or add listener for when they load
@private