The ornamental design for a chair, as shown and described.
FIG. 1 is a perspective view from the front and to one side of the chair;
FIG. 2 is a side elevational view of the chair of FIG. 1, the other side of
the chair being the mirror image of this view with the exception of the
controls for the chair;
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,