The ornamental design for a portabledeviceholder, as shown and described.
FIG. 1 is a front perspective view of a portable device holder showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side devotional view thereof, the right side elevational view being a mirror image thereof;
FIG. 5 is a top plan view thereof, the bottom plan view being a mirror image thereof;
FIG. 6 is a front perspective view thereof shown with the strap in a retracted condition of use;
FIG. 7 is a front perspective view thereof; shown with a portable device and human hand in broken lines to illustrate an environment; and,
FIG. 8 is a top perspective view thereof, shown with a substrate in broken lines to illustrate an environment.
The broken lines showing a portable device, a human hand and a substrate in FIGS. 7-8 represent environmental structure and form no part of the claimed design.