The ornamental design for a splashguard for a bathtub, as shown and described.
FIG. 1 is a perspective view of my new design showing a splash guard for a bathtub with the environment of use depicted in dotted lines and forming no part of the design thereof;
FIG. 2 is a perspective view of the splash guard of FIG. 1, the interrupted lines indicating that the length of the splash guard has been reduced for ease of illustration;
FIG. 3 is an end view of the splash guard of FIG. 1, the distal and proximal ends being mirror images of each other;
FIG. 4 is a front elevation of the splash guard of FIG. 1, the back elevation being a mirror image of the front, and the interrupted lines indicating that the length of the splash guard has been reduced for ease of illustration;
FIG. 5 is a top view of the splash guard of FIG. 1, the interrupted lines indicating that the length of the splash guard has been reduced for ease of illustration; and,
FIG. 6 is a bottom view of the splash guard of FIG. 1, the interrupted lines indicating that the length of the splash guard has been reduced for ease of illustration.