The ornamental design for a toiletseat for children, as shown and described.
FIG. 1 is a front, right, and top perspective view of a toilet seat for children, showing my new design;
FIG. 2 is a front, right, and bottom perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a left elevational view thereof;
FIG. 6 is a right elevational view thereof;
FIG. 7 is a top plan view thereof;
FIG. 8 is a bottom plan view thereof; and,
FIG. 9 is an enlarged view of the delineated region 9 in FIG. 7.
The dash broken lines depict portions of the toilet seat for children that form no part of the claimed design. The long dash-short dash broken lines in FIGS. 7 and 9 form no part of the claimed design and delineate portions of the claimed design that are shown on an enlarged scale in FIG. 9.