The ornamental design for a navigationdevice, as shown and described.
FIG. 1 is a front perspective view of a navigation device according to the present invention;
FIG. 2 is a rear perspective view of the navigation device;
FIG. 3 is a top view of the navigation device;
FIG. 4 is a front view of the navigation device;
FIG. 5 is a bottom view of the navigation device;
FIG. 6 is a rear view of the navigation device;
FIG. 7 is a left side view of the navigation device; and,
FIG. 8 is a right side view of the navigation device.
The structural features depicted by broken lines have been shown for the purpose of illustrating portions of the navigation device that form no part of the claimed design.