The ornamental design for a radiatorgrill for a vehicle, as shown and described.
FIG. 1 is a right perspective view of a radiator grill for a vehicle according to the design, the left perspective view being mirror symmetrical;
FIG. 2 is a front view thereof;
FIG. 3 is a top view thereof; and,
FIG. 4 is a right side view thereof, the left side view being mirror symmetrical.
The broken lines are for illustrative purposes only and form no part of the claimed design. Also enclosed is a set of photographs of an embodiment of the design.