Chair armrest and backrest interface

FIG. 1 is a front perspective view of a chair which includes an armrest and backrest interface according to our new design;

FIG. 2 is front perspective view thereof;

FIG. 3 is a rear perspective view thereof;

FIG. 4 is a side view thereof;

FIG. 5 is a top view thereof; and,

FIG. 6 is a rear view thereof.

Features shown in dashed lines form no part of the claimed design.