The ornamental design for a chair, as shown and described.
FIG. 1 is a perspective view of a chair showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a back view thereof;
FIG. 4 is a first side view thereof:
FIG. 5 is a second side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is perspective view showing the chair in an example environment.
The portions of the drawings shown dashed lines form no part of the claimed subject matter.
The broken away symbols in the drawings indicate the appearance of any portion of the article between the break lines forms no part of the claimed design.