Keep ::backdrop next to element in sync remove+add case
In the case that a top layer element is synchronously removed and
re-added to the top layer, it is supposed to get moved to the front of
the top layer list. However, its ::backdrop was not staying next to it
in the top layer list, which caused it to fall behind other top layer
elements.
This patch removes and re-adds any top layer element's ::backdrop when
it gets removed and re-added. This matches the rendering of firefox and
safari.
Fixed: 360158414
Change-Id: I3a619b248999a79139ced7a52591809e03e2a6c9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5788966
Commit-Queue: Joey Arhar jarhar@chromium.org
Reviewed-by: Rune Lillesveen futhark@chromium.org
Cr-Commit-Position: refs/heads/main@{#1345988}