The ornamental design for a topshell for portablebarcode scanner, as shown and described.
FIG. 1 shows a perspective view of the present design.
FIG. 2 shows a right side elevational view of the present design.
FIG. 3 shows a top plan view of the present design.
FIG. 4 shows a front elevational view of the present design.
FIG. 5 shows a bottom plan view of the present design.
FIG. 6 shows a left side elevational view of the present design.
FIG. 7 shows a rear elevational view of the present design; and,
FIG. 8 is a schematic drawing showing that the present design is assembled with a bottom shell for a barcode scanner, in which broken line illustration in the drawing is for illustrative purposes only and forms no part of the claimed design.