In https://gerrit.wikimedia.org/r/#/c/268185/ in Skin.js there is a setTimeout with 100 ms, that is because using requestAnimationFrame or setTimeout with a small delay (0, 10, etc) won't always trigger the CSS transition that fades the image in.
In chrome it is more blatant than in firefox for example, meaning that the transition won't get triggered with a small delay or raf.
Why is this happening? How do we get rid of the 100ms magic number? How do we reliably trigger the CSS transition when we want to?