The ornamental design for a flashlight with adapter, as shown and described.
FIG. 1 is a perspective view of the flashlight with an adapter;
FIG. 2 is another perspective view of the flashlight with an adapter;
FIG. 3 is a front view of the flashlight with an adapter;
FIG. 4 is a back view of the flashlight with an adapter;
FIG. 5 is a side view of the flashlight with an adapter;
FIG. 6 is a other side view of the flashlight with an adapter;
FIG. 7 is a bottom view of the flashlight with an adapter; and,
FIG. 8 is a top view of the flashlight with an adapter.
The broken lines in FIGS. 1 through 6 are of a battery pack that can be attached to the adapter to charge the flashlight. The battery pack is shown for illustrative purposes only and forms no part of the claimed design.