The ornamental design for a lightfixture, as shown and described.
FIG. 1 is a perspective view of a light fixture in accordance with my design, illustrating movable portions;
FIG. 2 is a side elevation view of the light fixture in accordance with my design the opposite view being a mirror image of that shown, illustrating movable portions; and,
FIG. 3 is a front elevation view of the light fixture in accordance with my design, illustrating movable portions.