When encountering a box that claims to have block-level children, but
its CSS display type isn't actually "flow" inside, we would previously
crash due to a VERIFY() failure.
However, many sites choke on this due to freestanding table-related
boxes like those created by "table-row" and "table-row-group".
We're supposed to fix those up by wrapping them in a full set of table
boxes during layout tree construction, but that algorithm obviously
isn't working correctly in all cases. So let's work around the crashes
for now, allowing many more sites to load (even if visually incorrect.)
This is a rather monstrous hack, and we should get rid of it as soon as
it's not needed anymore.