The ornamental design for a taillight for a vehicle, as shown and described.
FIG. 1 is a perspective view of a first embodiment of a taillight for a vehicle according to our design;
FIG. 2 is a front view thereof;
FIG. 3 is a side view thereof;
FIG. 4 is a top view thereof; and
FIG. 5 is a bottom view thereof.
FIG. 6 is a perspective view of a second embodiment of the taillight for a vehicle according to our design, with the taillight for a vehicle for the opposite side of the vehicle being depicted in the first embodiment;
FIG. 7 is a front view thereof;
FIG. 8 is a side view thereof;
FIG. 9 is a top view thereof; and,
FIG. 10 is a bottom view thereof.
The broken lines are for illustrative purposes only and form no part of the claimed design.