The ornamental design for baby chair, as shown and described.
FIG. 1 is a top, left, front perspective view of a baby chair showing my new design;
FIG. 2 is a front elevational view of the baby chair shown in FIG. 1;
FIG. 3 is a rear elevational view of the baby chair shown in FIG. 1;
FIG. 4 is a right side elevational view of the baby chair shown in FIG. 1;
FIG. 5 is a left side elevational view of the baby chair shown in FIG. 1;
FIG. 6 is a top plan view of the baby chair shown in FIG. 1; and,
FIG. 7 is a bottom plan view of the baby chair shown in FIG. 1.
The broken line showing of portions of the baby chair in FIG. 7 is included for the purpose of illustrating structure environment and forms no part of the claimed design.