The ornamental design for a childsafetyseat, as shown and described.
FIG. 1 is a top, front, right side perspective view of a child safety seat, showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a top, front, right side perspective view of the child safety seat of FIG. 1, shown in a condition of use with the side protector.
The broken lines in the drawings depict portions of the child safety seat that form no part of the claimed design. The broken lines showing the side protector in FIG. 8 depict environmental subject matter that forms no part of the claimed design.