The ornamental design for a tubecontainer, as shown and described.
FIG. 1 is a perspective view of the tube container showing my new design;
FIG. 2 is a top view thereof;
FIG. 3 is a bottom view thereof;
FIG. 4 is a front view thereof, the rear view being identical thereto; and,
FIG. 5 is a right side view thereof, the left side view being identical thereto.
The broken line showing of portions of the tube container is included for the purpose of illustrating environmental structure and forms no part of the claimed design.