The ornamental design for a portion of lightfixturehousing, as shown and described.
FIG. 1 is a perspective view from below of a portion of light fixture housing in accordance with my design; and,
FIG. 2 is a side elevation view of the portion of light fixture housing in accordance with my design, the opposite side being a mirror image of that shown.
The broken lines showing environmental structure are for illustrative purposes and form no part of the claimed invention.