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, 3A, 3B, 4, 5, 7A, 7B, 8, 9, 11A, 11B, 12, 13, 15A, 15B, 16, 17, 19A, 19B, 20, 21, 23A, 23B and 24 for illustrative purposes only and form no part of the claimed design. The broken lines in Figures 5, 6, 7A, 7B, 21, 22, 23A and 23B shown 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;Figures 3A and 3B are cross-sectional views of the LIGHT FIXTURE of figure 1 taken along the line 3A-3B 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;Figures 7A and 7B are cross-sectional views of the LIGHT FIXTURE of Figure 5 taken along the line 7A-7B 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;Figures 11A and 11B are cross-sectional views of the LIGHT FIXTURE of Figure 9 taken along the line 11A-11B 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;Figures 15A and 15B are cross-sectional views of the LIGHT FIXTURE of Figure 13 taken along the line 15A-15B 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;Figures 19A and 19B are cross-sectional views of the LIGHT FIXTURE of Figure 17 taken along the line 19A-19B 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;Figures 23A and 23B are cross-sectional views of the LIGHT FIXTURE of Figure 21 taken along the line 23A-23B 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.