The ornamental design for a flushometercover, as shown and described.
FIG. 1 is a front elevational view of a flushometer cover showing my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a bottom view thereof;
FIG. 5 is a right side view thereof; and,
FIG. 6 is a left side view thereof.
The broken lines shown in FIG. 1 illustrate environmental subject matter only that form no part of the claim. The broken lines shown in FIG. 4 depict portions of the flushometer cover that form no part of the claim.