The ornamental design for a crayonholder, as shown and described.
FIG. 1 is a right side perspective view of a crayon holder in accordance with the present invention;
FIG. 2 is a front elevation thereof;
FIG. 3 is a right side elevation thereof;
FIG. 4 is a top plan view thereof; and,
FIG. 5 is a bottom plan view thereof.
The broken lines showing a crayon in FIG. 1 are included for the purpose of showing an article in the environment that forms no part of the claimed design.