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.
The broken lines shown in the figures are included for the purpose of illustrating portions of the heat dissipation device that form no part of the claimed design.