The ornamental design for a naildryer, as shown and described.
FIG. 1 is a front elevational view of a nail dryer showing my design;
FIG. 2 is a back elevational view thereof;
FIG. 3 is a left side elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is a front, top and right-side perspective view thereof.
The dashed or broken lines shown in the drawings depict portions of the nail dryer in which the design is embodied that form no part of the claimed design.