code: function loadLargerImgSrc(img, largerSize) {
    if (img._preloaded) {
      return;
    }
  
    const dummyImg = new Image();
    dummyImg.srcset = img.srcset;
    dummyImg.sizes = largerSize;
  
    img._preloaded = true;
  }
docs: Loads an img using a srcset, with a larger `size` value. This does not
  actually set the `size` attribute on the img.