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; and,
FIG. 3 is a second perspective 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. The remaining broken lines represent portions of the fixture which form no part of the claimed design.