The ornamental design for a handlebarcover, as shown and described.
FIG. 1 is a perspective view of the handlebar cover, showing my new design;
FIG. 2 is a side elevational view thereof;
FIG. 3 is a front view thereof; and,
FIG. 4 is a plan view of a handlebar cover showing my new design in a configuration of use stretched onto the handgrip of a handlebar of an exercise device.
The structure shown in dashed lines represents unclaimed structure, is shown for exemplary purposes only, and does not form part of the claimed design.