This extends the fix in bug 1373802 to account for extra levels of
display item nesting. If those extra intermediate display items don't
push any clips we still want to pick up the ClipAndScroll from the
enclosing ancestor that has it.
MozReview-Commit-ID: AmxRz4fBKnX
--HG--
extra : rebase_source : ae12a9f797ab201169ff199d0d42a29df51ee1cb
Kartikaya Gupta