fix shared function reference issue when applying mixins

Enyo-DCO-1.1-Signed-off-by: Cole Davis <cole.davis@lge.com>
Merge pull request #260 from clinuz/ENYO-2284

ENYO-2284: Overloaded methods via mixins can inject a function to other kinds

Reviewed-By: Ben Combee (ben.combee@lge.com)