The ornamental design for a heatdissipationdevice, as shown and described.
FIG. 1 is a perspective view of a heat dissipation device showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left-side, elevational view thereof;
FIG. 5 is a right-side, elevational view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is a perspective view thereof, showing a cooling fan being mounted to the heat dissipation device, wherein the cooling fan is shown in broken lines for illustrative environmental purposes only and forms no part of the claimed design.