I claim the ornamental design for a chair, as shown and described.
FIG. 1 is a front and right side perspective view of a chair, showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
Any surface of the design not shown form no part of the claimed invention.
The fragmented crosshatch pattern shown on the upper solid area of the backrest and armrests represent fabric and is repeated throughout the areas shown.