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 left elevational view thereof;
FIG. 5 is a right elevational view thereof;
FIG. 6 is a back elevational view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.
The hortizontal broken line depicted at the top of the FIG. 3 through FIG. 6 represents environmental structure which forms no part of the claimed design, namely the ceiling to which the lighting fixture is mounted. The remaining broken line disclosures in the views represent portions of the lighting fixture which form no part of the claimed design.