SplitNodeDeepWithTransaction will split nodes until better point. But
this test case becomes that node is orphan into loop. So I would like to
add more check whether parent is nothing.
MozReview-Commit-ID: EroSV4uVBVL
--HG--
extra : rebase_source : f594bdf7cd9efac7d10e6e05a8f87dadfc761295