The ornamental design for a combatboot, as shown and described.
FIG. 1 is a right side perspective view of a combat boot according to our new design;
FIG. 2 is a front view of the combat boot of FIG. 1;
FIG. 3 is a back perspective view of the combat boot of FIG. 1;
FIG. 4 is a right side view of the combat boot of FIG. 1;
FIG. 5 is a left side view of the combat boot of FIG. 1; and,
FIG. 6 is a top view of the combat boot of FIG. 1.
The broken lines in the drawings are not part of the claimed design; and the cross-hatching is not a feature of the design but is utilized to illustrate the surface contours of the combat boot design in the drawings.