The ornamental design for a lightingdevice, as shown and described.
FIG. 1 is a front elevation view of a lighting device showing our new design;
FIG. 2 is a left side elevation view thereof;
FIG. 3 is a right side elevation view thereof;
FIG. 4 is a top plan view thereof; and,
FIG. 5 is a bottom plan view thereof.
The dashed broken lines in FIGS. 1-5 show unclaimed portions of the lighting device. The dashed-dotted broken lines in FIGS. 1-5 show an unclaimed boundary between claimed and unclaimed subject matter. The oblique line shading in FIGS. 1 and 5 show a translucent or transparent material. The remaining line shading in FIGS. 1-5 show surface contours, not surface ornamentation.