The ornamental design for a heatdissipationdevice, as shown and described.
FIG. 1 is a perspective view of a heat dissipation device showing our 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; and,
FIG. 7 is a bottom plan view thereof, wherein the features shown in broken lines are for illustrative purposes only and form no part of the claimed design.