We claim the ornamental design for a portable computer, as shown and described.
FIG. 1 is a front perspective view of the portable computer of the present invention;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a first side view thereof;
FIG. 5 is a second side view thereof;
FIG. 6 is a bottom view thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a cross-section view taken along the line 8-8 of FIG. 2.
The broken lines shown in the drawings represent portions of the portable computer which form no part of the claimed design. Additionally, the unevenly broken lines in the drawings define the limits of the claimed design.