The ornamental design for a storagebox, as shown and described.
FIG. 1 is a front view of a storage box showing our new design;
FIG. 2 is a rear view thereof;
FIG. 3 is a right side view thereof, the left side view being a mirror image;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a perspective view thereof;
FIG. 7 is a front view of the storage box in an open state;
FIG. 8 is a rear view thereof;
FIG. 9 is a right side view thereof, the left side view being a mirror image;
FIG. 10 is a top view thereof;
FIG. 11 is a bottom view thereof; and,
FIG. 12 is a perspective view thereof.
The broken lines illustrate portions of the storage box. The dash-dot-dash line broken lines illustrate the bounds of the claim. None of the broken lines or area within form part of the claimed design.