I claim the ornamental design for a toilet bowl, as shown and described.
FIG. 1 is a perspective view from above and the left of the toilet seat which is the subject of our new design;
FIG. 2 is a left side elevational view thereof, the right side elevational view being a mirror image thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a bottom plan view thereof.
The ornamental design which is claimed is shown in solid lines in the drawings. The broken lines in the drawings are for illustrative purposes only and form no part of the claimed design.