I claim the ornamental design for a cellphone holder, as shown and described.
FIG. 1 of the drawings is an isometric view showing the front, the top, and a first side of a cellphone holder embodying the design of my invention;
FIG. 2 is a front elevation view of the cellphone holder;
FIG. 3 is a back elevation view of the cellphone holder;
FIG. 4 is a left side elevation view showing the first side of the cellphone holder;
FIG. 5 is a right side elevation view showing a second side of the cellphone holder;
FIG. 6 is a top plan view;
FIG. 7 is a bottom view; and,
FIG. 8 is a reduced-in-scale environmental view showing the cellphone holder in its typical environment, with the cellphone holder clipped onto a top marginal edge portion of a computer video display shown in broken lines, where it is holding a cellphone shown in broken lines.
The portions shown in broken lines in FIG. 8 depict environmental subject matter and are for illustrative purposes only and form no part of the claimed design.