From the original email message [css3-regions] flow-into on inline or table-cell:
The spec says 'flow-into' applies to anything. If applied to inline elements, what are expectations for flow behavior - are inline elements concatenated in lines, or should there be an anonymous block for each one?
Also, if elements in flow are of the kind that normally require fixup (like table-cell), is it expected that fixup is performed separately in the composed flow, or would such elements change effective display type (e.g. table-cell would become a block unless it somehow ends up in a table-row)?
One thing we should point out is that the elements in the named flow have no whitespace separation. So if you have something like this:
What you get in the named flow is actually
So by moving the span elements from their markup parent (that contains the whitespace) you're changing what gets displayed from "one two" to "onetwo"
Fixed in https://dvcs.w3.org/hg/csswg/rev/b76903becabe