The ornamental design for an neckpillow with arm supports, as shown and described.
FIG. 1 is a front elevation view of an neck pillow with arm supports;
FIG. 2 is a rear elevation view thereof;
FIG. 3 is a right side elevational view thereof;
FIG. 4 is a left side, elevational view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is a front left perspective showing the neck pillow with arm supports.
The broken lines in the drawings illustrate portions of the neck pillow with arm supports, being stitching and pillow openings and retaining snaps that form no part of the claimed design.