An ornamentaldesign for a vehicle liftgate, as shown and described.
FIG. 1 is a top plan view of a vehicle liftgate;
FIG. 2 is a bottom plan view of the vehicle liftgate;
FIG. 3 is a front elevational view of the vehicle liftgate;
FIG. 4 is a left side elevational view of the vehicle liftgate;
FIG. 5 is a right side elevational view of the vehicle liftgate;
FIG. 6 is a perspective view of the vehicle liftgate; and,
FIG. 7 is another perspective view of the vehicle liftgate.
The broken lines and surface members shown in faded lighter tones and enclosed in broken lines are for illustrative purpose only and form no part of the claimed design.