Resolve every declaration on a chart into the layers they describe.
Runs in three passes, and the order matters: every declaration is read before
any companion is resolved, so a companion of a later layer is not swallowed
as an earlier layer's merged sibling, and every companion is absorbed before
the merge pass, so an absorbed series is never also an arm.
Resolve every declaration on a chart into the layers they describe.
Runs in three passes, and the order matters: every declaration is read before any companion is resolved, so a companion of a later layer is not swallowed as an earlier layer's merged sibling, and every companion is absorbed before the merge pass, so an absorbed series is never also an arm.