Hmm, I understand why you're using `skipped` now, but doing this means that pages will stay dirty after a checkpoint when they could be marked clean.  That is, it may lead to unnecessary I/O.

I don't know how often that will happen, but we really need two different things: a) there was an invisible update skipped before the one that was written (so a   future reconciliation could see a different value and the page should stay dirty) vs b) some update in the list can't be written in the `WT_SKIP_UPDATE_RESTORE` case, so the the update list should be saved.