static isImageInViewport(image, viewportDimensions) {
    const imageTop = image.clientRect.top;
    const viewportHeight = viewportDimensions.innerHeight;
    return imageTop < viewportHeight;
  }
@param {LH.Artifacts.ImageElement} image
@param {LH.Artifacts.ViewportDimensions} viewportDimensions
@return {boolean}