Issue #3285476 by vlad.dancer, smustgrave, seanB: ResizeObserver#observe()...

            const availableWidth = Math.floor(image.parentNode.clientWidth);

            const attrWidth = image.getAttribute('width');

            const sources = image.getAttribute('data-srcset').split(',');

            const currentSrc = image.getAttribute('src');

            // If the selected image is already bigger than the available width,

            // we do not update the image.

              }

            }

            if (responsiveImgPath === currentSrc) {

              return;

            }

            // Update the "src" with the new image and also set the "width"

            // attribute to easily check if we need a new image after resize.

            image.setAttribute('src', responsiveImgPath);