The ornamental design for a portablecomputer, as shown and described.
FIG. 1 is a perspective view of a portable computer showing our new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear 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 plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is a perspective view of another aspect of the portable computer, showing parts of the portable computer opened.
The broken lines shown in the figures form no part of the claimed design and the shade lines in the figures show contour and not surface ornamentation.