I claim the ornamental design for a scroll trellis, as shown and described.
FIG. 1 is a front elevational view of the scroll trellis showing my new design, the rear view of the scroll trellis being a minor image of the front view;
FIG. 2 is a first side elevational view thereof, the second side elevational view of the scroll trellis as seen from the side opposite that of FIG. 2 being a mirror image of FIG. 2;