moveBefore: keep current modal dialog when performing an atomic move.
We still update the a11y tree when we've performed that move as the
inert tree is updated.
Bug: 353441314
Change-Id: I369c6825394c89f2b01bd26a8f1c025cd1f98474
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5712819
Reviewed-by: Joey Arhar jarhar@chromium.org
Commit-Queue: Noam Rosenthal nrosenthal@chromium.org
Cr-Commit-Position: refs/heads/main@{#1344723}