The ornamental design for a storagebag, as shown and described.
FIG. 1 is a perspective view of the storage bag showing my new design;
FIG. 2 is a top view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a front view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a rear view thereof; and,
FIG. 7 is a left side view thereof.
The broken lines do not represent environmental structure and the words “DO FILL ABOVE THIS LINE” and “BAG MUST BE TOUCHING BOTTOM OF BIN” are included in and are part of the claimed design.