The ornamental design for an objectholder, as shown and described.
FIG. 1 is a front right perspective view of an object holder, showing my new design;
FIG. 2 is a rear left perspective view thereof;
FIG. 3 front elevation view thereof;
FIG. 4 is a back elevation view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.
The dash dot lines immediately adjacent to the claimed area represent the boundaries of the claimed design. The dashed lines in the figures illustrate the portions of the design that form no part of the claimed design. None of the broken lines form any part of the claimed design.