The ornamental design for a bottlestopper, as shown and described.
FIG. 1 is a front elevation view of a bottle stopper showing my new design; the rear elevation, left side elevation, and right side elevation views being a mirror image thereof;
FIG. 2 is a top view of the bottle stopper of FIG. 1;
FIG. 3 is a bottom view of the bottle stopper of FIG. 1;
FIG. 4 is a cross-sectional view of the bottle stopper taken in the direction of line 4-4 on FIG. 2;
FIG. 5 is a top perspective view of the bottle stopper of FIG. 1; and,
FIG. 6 is a bottom perspective view of the bottle stopper of FIG. 1.
In FIG. 2, the pair of arrows represent a sectional designation that forms no part of the claim.