Created attachment 174776 [details]
Testfile - display should read One Two Three
If you have an element in a named flow, and you add flow-into:none for a child of that element, the child stays in the named flow. If an element's flow-into property computes to none, it should not be included in a named flow.
Andrei Bucur pointed out that I was misinterpreting the spec. The flow-into property is not inherited, so all the children of an element moved into a named flow already have flow-into computing to 'none'. So setting this explicitly shouldn't make a difference.