ument.createElement('img');
            img.id = 'new_image_id';
            img.src = url;
            img.width = 100;
            beforeSecondImageLoad = performance.now();
            firstCallback = false;
            document.body.appendChild(img);
          } else {
            // Checks the new black rectangle.
            checkImage(entry, url, 'new_image_id', bigger_rect_size, beforeSecondImageLoad);
            t.done();
          }
        })
      );
      observer.observe({ type: 'largest-cont