The ornamental design for a supportpillow, as shown.
FIG. 1 is a top perspective view of a support pillow showing my new design;
FIG. 2 is a top plan view of the support pillow of FIG. 1;
FIG. 3 is a front elevation view of the support pillow of FIG. 1;
FIG. 4 is a bottom plan view of the support pillow of FIG. 1;
FIG. 5 is a rear elevation view of the support pillow of FIG. 1;
FIG. 6 is a left side elevation view of the support pillow of FIG. 1; and,
FIG. 7 is a right side elevation view of the support pillow of FIG. 1.
In the drawings, the closely spaced dotted broken lines on the exterior surfaces of the support pillow as illustrated in FIGS. 1-6, represent stitching forming part of the claimed design. In the drawings, the widely spaced dashed broken lines at the opening of the support pillow case illustrated in FIG. 1, FIG. 3 and FIG. 6 create a boundary to disclaim the interior region of the support pillow from the claimed design.