The ornamental design for a toolextension, as shown and described.
FIG. 1 is a front perspective view of a tool extension showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a left side elevational view thereof;
FIG. 7 is a right side elevational view thereof;
FIG. 8 is a rear perspective view thereof; and,
FIGS. 9, 10, 11, 12, 13 are front perspective views thereof, the tool stem depicted by means of broken lines shows unclaimed subject matter only and forms no part of the claimed design.