The ornamental design for a wastecassette, as shown and described.
FIG. 1 is a bottom perspective view of the waste cassette, showing my new design;
FIG. 2 is a top perspective view thereof;
FIG. 3 is a top view thereof;
FIG. 4 is a bottom view thereof;
FIG. 5 is a left side elevation view thereof;
FIG. 6 is a right side elevation view thereof;
FIG. 7 is a front view thereof; and,
FIG. 8 is a back view thereof.
The shading in the figures is fragmentarily shown for convenience of illustration, it being understood that the shading is uniformly continued over the surface on which it appears. The broken lines shown in the figures represent portions of the waste cassette that form no part of the claimed design.