The ornamental design for a flashlight, as shown and described.
FIG. 1 is a perspective view of a first embodiment of my flashlight;
FIG. 2 is front view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a back view thereof; and,
FIG. 6 is a top view thereof.
The oblique lines on the lenses of my design (as visible in FIGS. 1 and 6) indicate that they are at least translucent and may be transparent. The dashed lines in the figures form no part of the claimed design. All other surface(s) or portion(s) of my flashlight not shown in the figures or otherwise described in the specification, such as the bottom thereof and such as the locations behind the lenses, form no part of the claimed design.