We claim the ornamental design for an ironing board, as shown and described.
FIG. 1 is a perspective view of an ironing board showing the new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a left-side elevation view thereof;
FIG. 5 is a right-side elevation view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof;
FIG. 8 is a perspective view of the ironing board shown in a state of use;
FIG. 9 is a perspective view of the ironing board shown in a state of use in an alternate configuration; and,
FIG. 10 is a perspective view of the ironing board shown in a state of use in another alternate configuration.
The broken lines in FIGS. 1 to 7 represent portions of the ironing board that form no part of the claimed design. The broken lines in FIGS. 8 to 10 are included for the purpose of illustrating environmental structure and form no part of the claimed design.