The ornamental design for a portable powertool, as shown and described.
FIG. 1 is a front perspective view of a portable power tool in accordance with our new design;
FIG. 2 is a rear perspective view of the portable power tool in accordance with our new design;
FIG. 3 is a front elevational view of the portable power tool in accordance with our new design;
FIG. 4 is a rear elevational view of the portable power tool in accordance with our new design;
FIG. 5 is a top plan view of the portable power tool in accordance with our new design;
FIG. 6 is a bottom plan view of the portable power tool in accordance with our new design;
FIG. 7 is a right side elevational view of the portable power tool in accordance with our new design;
FIG. 8 is a left side elevational view of the portable power tool in accordance with our new design; and,
FIG. 9 is a front perspective view, similar to FIG. 1 of the portable power tool in accordance with our new design illustrating a state in which an attachment and a battery are attached to the portable power tool.
The broken line showing of environment forms no part of the claimed design.