The ornamental design for a chair, as shown and described.
FIG. 1 is a front perspective view of a chair in an unfolded state showing my design;
FIG. 2 is a rear perspective view of the chair in an unfolded state;
FIG. 3 is a top plan view of the chair in an unfolded state;
FIG. 4 is a bottom plan view of the chair in an unfolded state;
FIG. 5 is a right side elevation view of the chair in an unfolded state, the left side elevation view of the chair being a mirror image of the right side elevation view shown in FIG. 5;
FIG. 6 is a front elevation view of the chair in an unfolded state;
FIG. 7 is a rear elevation view of the chair in an unfolded state; and,
FIG. 8 is a cross-sectional view of the chair taken along line 8-8 of FIG. 6 in an unfolded state.
The broken lines are included for the purpose of illustrating environment of the design and form no part of the claimed design.