Fix HuberLoss.forward implementation to avoid cancellation of significant digits
Fix HuberLoss.forward implementation to avoid cancellation of significant digits

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