The ornamental design for a chair, as shown and described.
FIG. 1 is a perspective view of the chair;
FIG. 2 is a side elevational view of the chair of FIG. 1, the opposite side
being substantially a mirror image thereof with the addition of the two
adjacent levers which are seen in FIGS. 1, 3 and 4;
FIG. 3 is a front elevational view of the chair of FIG. 1;
FIG. 4 is a rear elevational view of the chair of FIG. 1; and,