The ornamental design for an extensionladderplatform, as shown and described.
FIG. 1 is a perspective view of an extension ladder platform showing my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a front elevation view thereof;
FIG. 5 is a rear elevation view thereof;
FIG. 6 is a left side elevation view thereof;
FIG. 7 is a right side elevation view thereof;
FIG. 8 is a view of the extension ladder platform showing a use thereof when mounted at a top portion of an extension ladder;
FIG. 9 is a view of the extension ladder platform showing a use thereof when mounted at a middle portion of an extension ladder; and,
FIG. 10 is a view of the extension ladder platform showing a use thereof when mounted at a bottom portion of an extension ladder.
The broken line in FIGS. 8-10 showing the extension ladder and the dashed line showing indicia in FIGS. 1, 2, 8, 9 and 10 are for illustrative purposes only and form no part of the claimed design.