moveBefore: only call FlatParentChanged for the directly inserted node.
To prevent from calling this on non-elements, ensure that the
StatePreservingAtomicMove flag is set only when the directly-moved
node is an element.
Bug: 352081025
Change-Id: I7f71c15509ad481d7d8c7e59fa60bc083d093a76
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5791021
Reviewed-by: Rune Lillesveen futhark@chromium.org
Commit-Queue: Noam Rosenthal nrosenthal@chromium.org
Cr-Commit-Position: refs/heads/main@{#1343487}