The ornamental design for a highchair, as shown and described.
The product has a cylindrical, vertical body, with a saddle seat attached on top. The back rest and safety guard are attached to the saddle seat from opposite directions. The foot rest is separately attached to the body.
FIG. 1 is a perspective front view of the highchair of the present invention;
FIG. 2 is a top view of the highchair shown in FIG. 1;
FIG. 3 is a front side view of the highchair shown in FIG. 1;
FIG. 4 is a left side view of the highchair shown in FIG. 1 ;
FIG. 5 is a rear view of the highchair shown in FIG. 1; and,
FIG. 6 is a bottom view of the highchair shown in FIG. 1.
The broken line showing in FIG. 6 is included for the purpose of illustrating environmental structure and forms no part of the claimed design.