The ornamental design for a lightfixture, as shown and described.
The single view is a top perspective view of a light fixture showing my new design, the broken-line defining the inner surface of the light fixture being understood to represent an unclaimed boundary between claimed and unclaimed areas. The characteristic feature of the claimed design resides in the presence of a horizontal striated pattern on the cylindrical surface of the light fixture.
The broken line surrounding the inner surface of the light fixture represents an unclaimed boundary of the design.