The ornamental design for a feedingbottlesterilizer, as shown and described.
FIG. 1 is a front perspective view of the feeding bottle sterilizer;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left view thereof where the right view is a mirror image;
FIG. 5 is a top view thereof;
FIG. 6 is a bottom view thereof; and,
FIG. 7 is a back perspective view thereof.
The broken lines depict portions of the feeding bottle sterilizer that form no part of the claimed design. The broken lines form no part of the claimed design.