Use common type when dtype is not given
Use common type when dtype is not given

hvy/chainer,wkentaro/chainer,hvy/chainer,keisuke-umezawa/chainer,wkentaro/chainer,aonotas/chainer,ktnyt/chainer,pfnet/chainer,okuta/chainer,niboshi/chainer,jnishi/chainer,keisuke-umezawa/chainer,tkerola/chainer,keisuke-umezawa/chainer,jnishi/chainer,chainer/chainer,ktnyt/chainer,wkentaro/chainer,rezoo/chainer,chainer/chainer,okuta/chainer,ktnyt/chainer,chainer/chainer,ronekko/chainer,keisuke-umezawa/chainer,anaruse/chainer,wkentaro/chainer,chainer/chainer,jnishi/chainer,niboshi/chainer,niboshi/chainer,ktnyt/chainer,niboshi/chainer,jnishi/chainer,hvy/chainer,okuta/chainer,okuta/chainer,hvy/chainer