The ornamental design for a chair, as shown and described.
FIG. 1 is a front elevational view of a chair showing my design;
FIG. 2 is a rear elevational view of the chair;
FIG. 3 is a right side elevational view of the chair;
FIG. 4 is a top plan view of the chair;
FIG. 5 is a bottom plan view of the chair; and,
FIG. 6 is a cross-sectional view of the chair taken along line 6-6 in FIG. 4.
The left side elevational view of the chair is omitted because it is a mirror image of the right side elevational view.
Throughout the Figures, portions represented by broken lines are not parts of the claimed design; the dot-and-dash lines show the boundaries of the claim and form no part thereof.