As mentioned in https://docs.gitlab.com/ce/development/fe_guide/performance.html#lazy-loading Currently, we have the following: - when an image is set to lazy load. We add the CSS class `lazy` to the HTML. - when an image is lazy loaded. We add the CSS class `js-lazy-loaded` using javascript. I propose, we change it to the following: - From `lazy` to `will-lazy-load` - From `js-lazy-loaded` to `lazy-loaded` We should remove the `js-` prefix because we've started to use it as a reference in our CSS as seen in https://gitlab.com/gitlab-org/gitlab-ce/blob/master/app/assets/stylesheets/framework/typography.scss#L24