The loading indicator *should* fade in after two seconds, to avoid a
flash of a loading indicator when the page loads quickly - but in some
circumstances it wouldn't delay:
1. Visit an item page. (It delays correctly the first time!)
2. Click "Infinite Closet", then click a link to another item page.
3. The loading indicator appears immediately, because this time the
web component JS is already loaded, so the `outfit-layer` elements
enter `:state(loading)` *immediately*. The element starts at
`opacity: 1`, and the delay doesn't matter, because it was never at
anything else.
In this change, we have the `outfit-viewer` web component take on a
`:state(after-first-frame)`, after a `setTimeout(0)` resolves. That
enables the loading state CSS to *never* apply on the first frame, but
then sometimes kick in on the *second* frame, so that the element is
correctly perceived as "transitioning" from hidden to visible, and the
two-second delay will apply.
Emi Matchu
d69c37089e