The ornamental design for a lightingfixture, as shown and described.
FIG. 1 is a top perspective view of a new lighting fixture;
FIG. 2 is a bottom perspective view thereof;
FIG. 3 is a front elevation view thereof.
FIG. 4 is a back elevational view thereof;
FIG. 5 is a left elevation view thereof;
FIG. 6 is a right elevation view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken line disclosure in the views represents environmental structure which forms no part of the claimed design. The broken-line square on the top surface of this lighting fixture is intended to demonstrate that no portion of this surface forms part of the claimed design.