The ornamental design for a trayholder, as shown and described.
FIG. 1 is a front top right-side perspective view of the tray holder of the present invention;
FIG. 2 is a front view thereof;
FIG. 3 is a back view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a bottom back left perspective view thereof.
The dash-dot-dash lines depict the boundary of the claim in FIGS. 1-8 and the evenly spaced broken lines in FIGS. 1-8 depict portions of the tray holder that form no part of the claimed design.