CRM_Utils_JS - also dedupe 'use strict' directive when deduping closures

[colemanw]

Overview

Improves JS closure deduping to remove redundant "use strict" directives.

Before

Useless redundant "use strict" directives littered around.

After

Remove all but the first one, as the js compiler will ignore the rest of them anyway.

[civibot]

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