The ornamental design for a toiletstool, substantially as shown and described.
FIG. 1 is a perspective view of a toilet stool, showing my new design;
FIG. 2 is a left side elevation view thereof, the right side elevational view being a mirror image thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a front elevation view thereof;
FIG. 5 is a top elevation view thereof; and,
FIG. 6 is a bottom elevation view thereof.
The broken lines showing foot pads in FIGS. 1, 3, and 5 and the structural ribbing in FIG. 6 depict environmental matter and form no part of the claimed design.