The ornamental design for a watchstrap, as shown and described.
FIG. 1 is a perspective view of a watch strap.
FIG. 2 is a bottom view of the watch strap of FIG. 1.
FIG. 3 is a top view of the watch strap of FIG. 1.
FIG. 4 is a side view of the watch strap of FIG. 1 taken from a first side.
FIG. 5 is a side view of the watch strap of FIG. 1 taken from a second side that is opposite the first side.
FIG. 6 is another perspective view of the watch strap of FIG. 1; and,
FIG. 7 is another side view of the watch strap of FIG. 1.
The broken lines in the drawings showing a watch represent environmental subject matter only that forms no part of the claimed design. The other broken lines on the watch band correspond to stitching that is part of the claimed design.