The ornamental design for a portablecomputer, as shown and described.
FIG. 1 is a top front perspective view of a portable computer showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a side view thereof;
FIG. 5 is another side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a top rear perspective view thereof, with the portable computer shown in an open position.
The broken lines illustrating portions of the portable computer are for environmental purposes only and form no part of the claimed design. The dot dash broken lines define boundaries of the claimed design and form no part thereof.