The ornamental design for a bathtubtray, as shown and described.
FIG. 1 is a front elevation view of a bath tub tray showing my new design;
FIG. 2 is a rear elevation view thereof;
FIG. 3 is a left side elevation view thereof;
FIG. 4 is a right side elevation view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is a top front side perspective view of the bath tub tray in use.
The broken line showing of parts of the drawings is included for the purpose of illustrating use and environment and forms no part of the claimed design.