Support flex-items with content and no 'flex' or width defined

[pci]

Continuing the discussion from here.

On content within flex items: the firefox implementation (in nightly and aurora) seems much more sane - for /comprehensive it makes three even columns. So at best the spec doesn't specify what to do in this situation and we can follow the firefox model, at worse we're missing something in the spec which means that chrome has the correct rendering. Is it worth emailing the webkit mailing list to ask how the layout is determined in these cases, and whether it's spec driven?