The ornamental design for a christmastreetin, as shown and described.
FIG. 1 illustrates a perspective view of a Christmas tree tin of the present invention;
FIG. 2 illustrates a top view of the Christmas tree tin of the present invention;
FIG. 3 illustrates a front view of the Christmas tree tin of the present invention, the back view, the right side view and the left side view thereof being the same as the front view; and,
FIG. 4 illustrates a bottom view of the Christmas tree tin of the present invention.
The broken lines of FIGS. 1–4 are for illustrative purposes only and form no part of the claimed design.