Add test for Array::AsConstant() as deep copy
Add test for Array::AsConstant() as deep copy

hvy/chainer,keisuke-umezawa/chainer,jnishi/chainer,niboshi/chainer,keisuke-umezawa/chainer,keisuke-umezawa/chainer,niboshi/chainer,wkentaro/chainer,jnishi/chainer,hvy/chainer,ktnyt/chainer,niboshi/chainer,pfnet/chainer,wkentaro/chainer,hvy/chainer,okuta/chainer,hvy/chainer,wkentaro/chainer,chainer/chainer,okuta/chainer,chainer/chainer,tkerola/chainer,ktnyt/chainer,jnishi/chainer,wkentaro/chainer,okuta/chainer,chainer/chainer,chainer/chainer,ktnyt/chainer,ktnyt/chainer,keisuke-umezawa/chainer,jnishi/chainer,niboshi/chainer,okuta/chainer