The ornamental design for a shockliner, as shown and described.
FIG. 1 is a top perspective view of a shock liner showing the new design, the precise length of the shock liner is not claimed;
FIG. 2 is a top view thereof;
FIG. 3 is a bottom view thereof;
FIG. 4 is a front view thereof, the back view being the same image thereof;
FIG. 5 is a right side view thereof, the left side view being the same image thereof; and,
FIG. 6 is a top perspective view thereof of the design in the context in which it is intended to be used, the dashed lines form no part of the claimed design.
The design is shown broken apart along its length to indicate that no specific length is claimed.