The ornamental design for a combine harvester, as shown and described.
FIG. 1 is a front, right perspective view of a combine harvester showing the new design;
FIG. 2 is a front, left perspective view of a combine harvester showing the new design;
FIG. 3 is a right side view of the combine harvester;
FIG. 4 is a left side view of the combine harvester;
FIG. 5 is a front view of the combine harvester;
FIG. 6 is a rear view of the combine harvester; and,
FIG. 7 is a top view of the combine harvester.
The broken line showing of the top and bottom portions of a combine harvester is included for the purpose of illustrating environmental structure and forms no part of the claimed design.