The ornamental design for a lightingfixture, as shown and described.
FIG. 1 is a front perspective view of a lighting fixture depicting a new design;
FIG. 2 is a back perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a left elevational view thereof;
FIG. 5 is a right elevational view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is a back elevational view thereof.
The vertical broken lines in FIGS. 4 and 5 and the horizontal broken lines in FIGS. 6 and 7 represent environmental structure which forms no part of the claimed design. The remaining broken line disclosures in the views represent portions of the lighting fixture which form no part of the claimed design.