The ornamental design for an infantsleepingaid, as shown and described.
FIG. 1 is a front elevation view of an infant sleeping aid;
FIG. 2 is a rear elevation view thereof;
FIG. 3 is a left side elevation view thereof;
FIG. 4 is a right side elevation view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a front perspective view thereof.
The broken lines of FIGS. 1-7 illustrate portions of the infant sleeping aid, or illustrate environmental matter, that form no part of the claimed design.