[css-overflow] What's the behavior of overflow:scroll on replaced elements?

[tabatkins]

In #7714 it was resolved that overflow: hidden on replaced elements should become clip at used-value time (and, separately, that certain other spec concepts specifically check the computed value).

That resolution (and the associated minutes) don't define what to do with the other value that normally establishes scrollable overflow, scroll. (And auto, when needed.) What should be the behavior there?

Currently we've editted the spec just to do the transform on hidden->clip.