The ornamental design for a lightfixtureadapterplate, as shown and described.
FIG. 1 is a perspective view of a light fixture adapter plate;
FIG. 2 is a top view of a light fixture adapter plate;
FIG. 3 is a bottom view of a light fixture adapter plate;
FIG. 4 is a view of the front side of a light fixture adapter plate;
FIG. 5 is a view of the back side of a light fixture adapter plate;
FIG. 6 is a view of the left side of a light fixture adapter plate;
FIG. 7 is a view of the right side of a light fixture adapter plate; and,
FIG. 8 is another perspective view showing the light fixture adapter plate in its environment of use.
The broken lines shown in FIG. 3 and FIG. 7 illustrate portions of the light fixture adapter plate that form no part of the claimed design. The broken lines in FIG. 8 illustrate environmental structure that forms no part of the claimed design.