The ornamental design for a footrestheater, as shown and described.
FIG. 1 is a top perspective view of the footrest heater;
FIG. 2 is a front elevational view of the footrest heater of FIG. 1;
FIG. 3 is a rear elevational view of the footrest heater of FIG. 1;
FIG. 4 is a left elevational view of the footrest heater of Fig.;
FIG. 5 is a right elevational view of the footrest heater of FIG. 1;
FIG. 6 is a top plan view of the footrest heater of FIG. 1; and,
FIG. 7 is a bottom plan view of the footrest heater of FIG. 1.
The broken lines shown in the openings of the vertical slots in FIG. 3, the circular pattern on the bottoms of the four support feet and the bottom surface of the foot rest heater adjacent to front edge in FIG. 7 is included for the purpose of illustrating environment and forms no part of the claimed design.