The ornamental design for a supportbracket, as shown and described.
FIG. 1 is a perspective view of a support bracket according to the invention;
FIG. 2 is a top view of the support bracket of FIG. 1;
FIG. 3 is a bottom view of the support bracket of FIG. 1;
FIG. 4 is a left side view of the support bracket of FIG. 1;
FIG. 5 is a right side view of the support bracket of FIG. 1;
FIG. 6 is a front view of the support bracket of FIG. 1;
FIG. 7 is a rear view of the support bracket of FIG. 1;
FIG. 8 is a perspective view of the support bracket of FIG. 1 shown on the underside of a flooring panel and with a support leg and pin shown in broken lines; and,
FIG. 9 is another perspective view of FIG. 8.
The broken line drawings of the flooring panel, support leg and pin in FIG. 8 and FIG. 9 are for illustrative purposes only and form no part of the claimed design.