Bathtub

FIG. 1 is a first perspective view of a bathtub showing my new design; FIG. 2 is a second perspective view thereof; FIG. 3 is a front view of FIG. 1 ; FIG. 4 is a rear view of FIG. 1 ; FIG. 5 is a left side view of FIG. 1 ; FIG. 6 is a right side view of FIG. 1 ; FIG. 7 is a top plan view of FIG. 1 ; and, FIG. 8 is a bottom plan view of FIG. 1 . The broken lines show portions of the bathtub that form no part of the claimed design.