I claim, the ornamental design for a chair, as shown and described.
FIG. 1 is a perspective view of a chair, showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a side view thereof;
FIG. 5 is an opposite side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
Portions shown in broken lines represent seam lines in the front cushion of the chair and form no part of the claimed design. With the exception of these broken line portions, all other portions within the solid line that traces the outer edge of the front cushion, as seen in FIGS. 1-6, form part of the claimed design.