The ornamental design for a watchcase, as shown and described.
FIG. 1 is an enlarged perspective view of a watchcase showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a left side elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a rear elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The portion of the photograph shown in a light gray tone, along with the broken line perimeter thereof, illustrates the portion of the watchcase that forms no part of the claimed design.