The ornamental design for a platformadapter, as shown and described.
FIG. 1 is a top, front, right side isometric view of a platform adapter showing my new design;
FIG. 2 is a bottom, rear, left side isometric view of the platform adapter shown in FIG. 1;
FIG. 3 is a front view of the platform adapter shown in FIG. 1;
FIG. 4 is a right side view of the platform adapter shown in FIG. 1;
FIG. 5 is a rear view of the platform adapter shown in FIG. 1;
FIG. 6 is a left side view of the platform adapter shown in FIG. 1;
FIG. 7 is a top view of the platform adapter shown in FIG. 1; and,
FIG. 8 is a bottom view of the platform adapter shown in FIG. 1.
The evenly broken lines shown in the drawings represent portions of the platform adapter that form no part of the claimed design. The unevenly broken lines represent the bounds of the claim and form no part thereof.