The ornamental design for a lightfixture, as shown and described.
FIG. 1 is a first perspective view of a light fixture showing our new design;
FIG. 2 is a bottom view thereof;
FIG. 3 is a second perspective view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a front view thereof;
FIG. 6 is a rear view thereof;
FIG. 7 is a right side view thereof; and,
FIG. 8 is a left side view thereof.
The uneven-length broken lines immediately adjacent to the shaded areas represent an unclaimed boundary of the claim, and the area between those lines forms no part of the claimed design.