The ornamental design for a chair, as shown and described.
FIG. 1 is a perspective view of a chair showing my design;
FIG. 2 is a front elevational view of the chair;
FIG. 3 is a rear elevational view of the chair;
FIG. 4 is a right side elevational view of the chair;
FIG. 5 is a left side elevational view of the chair;
FIG. 6 is a top plan view of the chair;
FIG. 7 is a bottom plan view of the chair;
FIG. 8 is a cross-sectional view of the chair taken in the direction of line 8-8 shown in FIG. 6; and,
FIG. 9 is an enlarged fragmentary view of the left end of FIG. 8.
In the drawings, the dash-dash broken lines show portions of the chair that form no part of the claimed design. The dot-dash-dot broken lines represent the boundaries of the claim and form no part thereof.