The design is the shape of the LIGHT FIXTURE shown in the Drawings. Figures 1, 2, 4, 5, 6, 8, 9, 10, 12, 13, 14, 16, 17, 18, 20, 21, 22 and 24 are broken away to indicate indeterminate length. The broken lines are shown in Figures 1, 3, 4, 5, 7, 8, 9, 11, 12, 13, 15, 16, 17, 19, 20, 21, 23 and 24 for illustrative purposes only and form no part of the claimed design. The broken lines in Figures 5, 6, 7, 21, 22 and 23 on the respective end faces of the LIGHT FIXTURE are for illustrative purposes only and form no part of the claimed design. Drawings of the design are included, in which:Figure 1 is a perspective view of the LIGHT FIXTURE;Figure 2 is a bottom plan view of the LIGHT FIXTURE of Figure 1;Figure 3 is a cross-sectional view of the LIGHT FIXTURE of Figure 1 taken along the line 3-3 in Figure 2;Figure 4 is a cross-sectional view of the LIGHT FIXTURE of Figure 1 taken along the line 4-4 in Figure 2;Figure 5 is a perspective view of a second variant of the LIGHT FIXTURE;Figure 6 is a bottom plan view of the LIGHT FIXTURE of Figure 5;Figure 7 is a cross-sectional view of the LIGHT FIXTURE of Figure 5 taken along the line 7-7 in Figure 6;Figure 8 is a cross-sectional view of the LIGHT FIXTURE of Figure 5 taken along the line 8-8 in Figure 6;Figure 9 is a perspective view of a third variant of the LIGHT FIXTURE;Figure 10 is a bottom plan view of the LIGHT FIXTURE of Figure 9;Figure 11 is a cross-sectional view of the LIGHT FIXTURE of Figure 9 taken along the line 11-11 in figure 10;Figure 12 is a cross-sectional view of the LIGHT FIXTURE of Figure 9 taken along the line 12-12 in Figure 10;Figure 13 is a perspective view of a fourth variant of the LIGHT FIXTURE;Figure 14 is a bottom plan view of the LIGHT FIXTURE of Figure 13;Figure 15 is a cross-sectional view of the LIGHT FIXTURE of Figure 13 taken along the line 15-15 in Figure 14;Figure 16 is a cross-sectional view of the LIGHT FIXTURE of figure 13 taken along the line 16-16 in Figure 14;Figure 17 is a perspective view of a fifth variant of the LIGHT FIXTURE;Figure 18 is a bottom plan view of the LIGHT FIXTURE of Figure 17;Figure 19 is a cross-sectional view of the LIGHT FIXTURE of Figure 17 taken along the line 19-19 in Figure 18;Figure 20 is a cross-sectional view of the LIGHT FIXTURE of Figure 17 taken along the line 20-20 in Figure 18;Figure 21 is a perspective view of a sixth variant of the LIGHT FIXTURE;Figure 22 is a bottom plan view of the LIGHT FIXTURE of Figure 21;Figure 23 is a cross-sectional view of the LIGHT FIXTURE of Figure 21 taken along the line 23-23 in Figure 22; andFigure 24 is a cross-sectional view of the LIGHT FIXTURE of Figure 21 taken along the line 24-24 in figure 22.