The ornamental design for an chair, as shown and described.
FIG. 1 is a perspective view of a chair according to the invention;
FIG. 2 is a top plan view of the chair shown in FIG. 1;
FIG. 3 is a front elevational view of the chair shown in FIG. 1; and
FIG. 4 is a side elevational view of the chair shown in FIG. 1.
The side of the chair not shown is a mirror image of the side shown in FIG.
4 while the undisclosed rear surface of the backrest is like the front
thereof.