FIG. 1 is a front perspective view of a backrest showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a right side elevational view therof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is a front perspective view, shown with a pillow engaged.
The broken line showing of a pillow in FIG. 8 is included for the purpose of illustrating only and forms no part of the claimed design.