I claim the ornamental design for a light for helmet, as shown and described herein.
FIG. 1. Is a perspective view of my light for helmet with the dotted lines showing being for illustrative purposes only and to which no claim is made;
FIG. 2. Is a right side elevational view thereof with the left side view being a mirror image thereof and with the dotted lines showing being for illustrative purposes only and to which no claim is made;
FIG. 3. Is a front view thereof with the dotted lines showing being for illustrative purposes only and to which no claim is made;
FIG. 4. Is a rear view thereof with the dotted lines showing being for illustrative purposes only and to which no claim is made;
FIG. 5. Is a top view thereof with the dotted lines showing being for illustrative purposes only and to which no claim is made; and,
FIG. 6. Is a bottom view thereof with the dotted lines showing being for illustrative purposes only and to which no claim is made.