The ornamental design for a lightingfixture, as shown and described.
FIG. 1 is a perspective view a lighting fixture in accordance with the new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a left side elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a perspective view of another embodiment of the lighting fixture with an upper portion being opaque and a lower portion being transparent or translucent in accordance with the new design;
FIG. 7 is a front elevational view thereof;
FIG. 8 is a left side elevational view thereof;
FIG. 9 is a right side elevational view thereof; and,
FIG. 10 is a bottom view thereof.
The broken lines showing portion of the lighting fixture in the figures illustrate environmental structures and form no part of the claimed invention.