The ornamental design for a chair, as shown and described.
FIG. 1 is a perspective view of the chair embodying my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a front elevational view thereof;
FIG. 5 is a rear elevational view thereof; and,
FIG. 6 is a right side elevational view thereof, the left side elevational view being a mirror image thereof.
FIGS. 1–6 show portions of the chair in broken lines. These features are shown for environmental purposes and do not form any part of the claimed design.