LayoutPhase::InRenderTreeLayout shouldn't re-curse into another layout.
Pull request: https://github.com/WebKit/WebKit/pull/13773
Committed 264051@main (a5dadd583b24): <https://commits.webkit.org/264051@main> Reviewed commits have been landed. Closing PR #13773 and removing active labels.
<rdar://problem/109308161>
Re-opened since this is blocked by bug 259381