Cooking appliance grate

The design is the features of shape, configuration, pattern and ornament of the gas cooktop as shown in solid lines in the drawings. The portions shown in stippled lines do not form part of the design. Drawings of the design are included wherein: Figure 1 is a perspective view of the gas cooktop; Figure 2 is a top view thereof; Figure 3 is a bottom view thereof; Figure 4 is a front view thereof; Figure 5 is a rear view thereof; and Figure 6 is a right side view thereof.