The ornamental design for a wristwatchcase, as shown and described.
FIG. 1 is a bottom right isometric view of the front of the wrist watch case, which embodies my design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is an end elevation view thereof;
FIG. 5 is a side elevation view thereof; and,
FIG. 6 is a second bottom right isometric view thereof, shown in use.
The watch strap depicted by broken lines in FIG. 6 has been shown for the purpose of illustrating an environmental feature that forms no part of the claimed design.