I claim the ornamental design for a lighting device, as shown and described.
FIG. 1 is a perspective view of a lighting device showing my new design, as viewed from the top and one side.
FIG. 2 is a first side elevation view of the lighting device of FIG. 1, the opposite side being a mirror image thereof.
FIG. 3 is a top plan view of the lighting device of FIG. 1.
FIG. 4 is a front elevation view of the lighting device of FIG. 1.
FIG. 5 is a back elevation view of the lighting device of FIG. 1.
FIG. 6 is a bottom plan view of the lighting device of FIG. 1; and,
FIG. 7 is a perspective view of the lighting device of FIG. 1 with the front light head and its associated support arms, and the back light head shown in a slightly rotated position.
The details shown in broken lines illustrate portions of the lighting device that form no part of the claimed design.