(splitting out the DOM update issue (#55933 (comment)) from shadow inconsistency issue (#55933))

When we remove an RRect with a shadow, sometimes Safari would still show the shadow from the element (albeit it does remove the rounded corners). In the example below, the rectangle surrounding the "200 x 200" image with a shadow does not actually exist in the DOM. It used to exist on a previous frame as an element with rounded corners and a shadow.

This does not happen in Chrome or Firefox.

Repro: the original repro steps in #55933 demonstrate this issue (here it is hosted: https://flwtbeta.netlify.app/#/)