The ornamental design for a lightfixture, as shown and described.
FIG. 1 is a front perspective view of a light fixture according to the new design;
FIG. 2 is a rear perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a left side view thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
The broken lines in the drawings illustrate portions of the light fixture the form no part of the claimed design. The appearance of any portion of the light fixture located between the break lines forms no part of the claimed design.