The ornamental design for a nailpolishingdevice, as shown and described.
FIG. 1 is a first perspective view of a nail polishing device showing my new design;
FIG. 2 is a second perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is aback view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
The broken lines shown in the drawings depict portions of the nail polishing device in which the design is embodied that form no part of the claimed design.