The ornamental design for a furnituresupport, as shown and described.
FIG. 1 is a front side view of a design for a furniture support.
FIG. 2 is a back side view of the design of the furniture support.
FIG. 3 is a right side view of the design of the furniture support.
FIG. 4 is a left side view of the design of the furniture support.
FIG. 5 is a bottom view of the design of the furniture support.
FIG. 6 is a bottom perspective view of the design of the furniture support; and,
FIG. 7 is a bottom perspective view of the design of the furniture support.
The broken lines showing a surface being supported by the furniture support, and couplings for attaching the furniture support to the surface being support are for illustrative purposes only and form no part of the claimed design.