The ornamental design for a toiletstep for children, as shown and described.
FIG. 1 is a front view of a toilet step for children;
FIG. 2 is a right side view thereof, the left side view being a mirror image;
FIG. 3 is a top side view thereof;
FIG. 4 is a lower side view thereof;
FIG. 5 is a back view thereof;
FIG. 6 is an isometric view thereof; and,
FIG. 7 is a different isometric view thereof showing the toilet step for children in a condition of use.
The even segmented lines drawn in FIGS. 2-7 are unclaimed adjustable supports, and which forms no part of the claimed design. The dash dot lines shown in FIG. 7 are for purposes of illustrating environmental structure associated with the claimed design in condition of use, and which forms no part of the claimed design.