The ornamental design for a flagholder, as shown and described.
FIG. 1 is a front perspective view of a first embodiment of a flag holder showing the new design;
FIG. 2 is a rear perspective view thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a bottom plan view thereof;
FIG. 5 is a front elevation view thereof;
FIG. 6 is a rear elevation view thereof;
FIG. 7 is a right side elevation view thereof;
FIG. 8 is a left side elevation view thereof;
FIG. 9 is a side view thereof showing the flag holder in a position of use seated in the ground and holding a flag;
FIG. 10 is a front perspective view of a second embodiment of the flag holder wherein a drain hole is included; and,
FIG. 11 is a front elevation view thereof.
The broken lines in FIG. 9 depict environmental subject matter that forms no part of the claimed design. Views not shown in the second embodiment are identical to FIGS. 2-4 and 6-8 of the first embodiment.