When parser appends multiple child nodes to a node disconnected from the rest of DOM tree, we can coalesce childrenChanged calls.
Pull request: https://github.com/WebKit/WebKit/pull/23453
Committed 273720@main (21d657acd1ba): <https://commits.webkit.org/273720@main> Reviewed commits have been landed. Closing PR #23453 and removing active labels.
<rdar://problem/121902509>