ENYO-1269: fixed array concatenation

concat returns the new array. Hence the concatenated array was lost.

Here a push must be used to update inplace the targer array. 

This fix was tested on Firefox 10 (with an unrelated hack around enyo.Blob that I'm going to push)

Enyo-DCO-1.1-Signed-off-by: Dominique Dumont <dominique.dumont@hp.com>