The ornamental design for a vinylcornerplinth, as shown and described.
FIG. 1 is a perspective view showing my new design for a vinyl corner plinth;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a front elevational view thereof;
FIG. 5 is a left side elevational view thereof;
FIG. 6 is a right side elevational view thereof; and,
FIG. 7 is a rear elevational view thereof.
The broken lines in the drawing views are included for the purpose of illustrating portions of the vinyl plinth that form no part of the claimed design.