The ornamental design for a jigsaw, as shown and described.
FIG. 1 is a side view of a jigsaw in accordance with the present teachings.
FIG. 2 is an opposite side view of the jigsaw of FIG. 1.
FIG. 3 is a front view of the jigsaw of FIG. 1.
FIG. 4 is a rear view of the jigsaw of FIG. 1.
FIG. 5 is a top view of the jigsaw of FIG. 1, a bottom view of the jigsaw is excluded because the view is almost entirely obstructed by a cutting shoe shown in broken line; and,
FIG. 6 is a perspective view of the jigsaw of FIG. 1.
The broken line showing of portions of the jigsaw forms no part of the claimed design.