The ornamental design for a lightingfixture, as shown and described.
FIG. 1 is a bottom plan view of a lighting fixture showing the new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a back elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a left side elevational view thereof;
FIG. 6 is a bottom perspective view thereof; and,
FIG. 7 is a top perspective view thereof.
The broken lines shown on the top surface of the lighting fixture in FIGS. 1 and 7 illustrate a portion of the lighting fixture that forms no part of the claimed design. The remaining broken lines shown in FIGS. 1-7 illustrate environmental structure that forms no part of the claimed design.