dillon1000/react

Clear width/height from Keyframes to Optimize View Transitions (#33576)

View Transitions has this annoying quirk where it adds `width` and
`height` to keyframes automatically when generating keyframes even when
it's not needed. This causes them to deopt from running on the
compositor thread in both Chrome and Safari. @bramus has a [good article
on
it](https://www.bram.us/2025/02/07/view-transitions-applied-more-performant-view-transition-group-animations/).

In React we can automatically rewrite the keyframes when we're starting
a View Transition to drop the `width` and `height` from the keyframes
when they have the same value and the same value as the pseudo element.

To compare it against the pseudo element we first apply the new
keyframes without the width/height and then read it back to see if it
has changed. For gestures, we have already cancelled the previous
animation so we can just read out from that.