I claim the ornamental design for a portable electronic device, as shown and described.
FIG. 1 is a front/right-side/top perspective view of a portable electronic device showingmy new design;
FIG. 2 is a front-side elevational view thereof;
FIG. 3 is a rear-side elevational view thereof;
FIG. 4 is a left-side elevational view thereof;
FIG. 5 is a right-side elevational view thereof;
FIG. 6 is a top-side elevational view thereof;
FIG. 7 is a bottom-side elevational view thereof; and,
FIG. 8 is a perspective view thereof.
The broken lines throughout the views are for illustrative purposes only and show portions of the portable electronic device that form no part of the claimed design.