The ornamental design for a watercloset, as shown and described.
FIG. 1 is a top, right, front, perspective view of a water closet showing our new design;
FIG. 2 is a top, right, rear, perspective view thereof;
FIG. 3 is a top, left, rear, perspective view thereof;
FIG. 4 is a front view thereof;
FIG. 5 is a rear view thereof;
FIG. 6 is a left side view thereof;
FIG. 7 is a right side view thereof;
FIG. 8 is a top view thereof; and,
FIG. 9 is a bottom view thereof.
The broken lines shown in the figures are included for the purpose of illustrating portions of the water closet that form no part of the claimed design.