The ornamental design for an electric standlight, as shown and described.
FIG. 1 is a perspective view of the electric stand light;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines are included for the purpose of illustrating the unclaimed portions of the article, namely, the base of the electric stand light, and form no part of the claim.