The ornamental design for a frontgrille for a vehicle, as shown and described.
FIG. 1 is a left, front perspective view of a grille for a vehicle showing my new design;
FIG. 2 is a right, rear perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is right side view thereof;
FIG. 7 is a top view thereof;
FIG. 8 is a bottom view thereof; and,
FIG. 9 is another front elevational view thereof shown on a vehicle.
The portions of the vehicle shown in the FIG. 9 drawing view in de-emphasized and half-tone form outside the broken lines and the broken lines representing the boundary and configuration of what is claimed as the design are for environmental and illustrative purposes and form no part of the claimed design.