The ornamental design for a lightingfixture, as shown and described.
FIG. 1 is a top perspective view of a lighting fixture depicting a new design;
FIG. 2 is a bottom perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a back elevational view thereof;
FIG. 5 is a right elevational view thereof;
FIG. 6 is a left elevational view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.
The horizontal broken lines extending out beyond the perimeter of the top surface of the fixture in FIGS. 3-6 is intended to demonstrate environment only and forms no part of the claimed design. The remaining broken line disclosure in the views represents portions of the lighting fixture that form no part of the claimed design.