Update product.js

if product with declinaison without reduction : reduction price is showed !!

because of this comparison after (line ~400):

if (productPriceWithoutReductionDisplay > productPriceDisplay)

and :

var tmp = productPriceDisplay * group_reduction;

is unused
Merge pull request #584 from Captain-FLAM/patch-3

[-] FO : product with declinaisons without reductions, reduction price is showed anyway