The ornamental design for a lightingdevice, as shown and described.
FIG. 1 is a perspective view of a lighting device showing the claimed design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The segmental shaft body depicted in FIGS. 2, 3, 4, and 5 illustrate that its length is not limited, whereas the broken lines of all of the figures are directed to environment and are for illustrative purposes only for forming no part of the claimed design.