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Description
In #6026 we resolved to restore the rule that made viewport units account for overflow: scroll. But this is only part of the equation: it doesn't handle overflow: auto. The restriction was put in originally because cycling computed style after layout was complicated.
But since the dv* units are already dynamic, and are relatively new so have fewer compat restrictions, should they be made to dynamically account for scrollbars?
If so, should we adjust the sv* units also?