Rule: unnecessary-strict

The `unnecessary-strict` rule flags the use of the `"use strict";` directive when already in strict mode.

"use strict";
(function () {
    "use strict";
    var foo = true;
}());

See http://jslinterrors.com/unnecessary-use-strict/
Merge pull request #197 from iancmyers/rule-unnecessary-strict

Rule: unnecessary-strict