Add more tests for scalar.
Add more tests for scalar.

wkentaro/chainer,wkentaro/chainer,niboshi/chainer,cupy/cupy,niboshi/chainer,ronekko/chainer,ktnyt/chainer,jnishi/chainer,ktnyt/chainer,kashif/chainer,wkentaro/chainer,ktnyt/chainer,hvy/chainer,okuta/chainer,niboshi/chainer,hvy/chainer,chainer/chainer,hvy/chainer,jnishi/chainer,hvy/chainer,chainer/chainer,niboshi/chainer,keisuke-umezawa/chainer,cupy/cupy,cupy/cupy,okuta/chainer,pfnet/chainer,kiyukuta/chainer,keisuke-umezawa/chainer,rezoo/chainer,wkentaro/chainer,jnishi/chainer,delta2323/chainer,jnishi/chainer,chainer/chainer,chainer/chainer,keisuke-umezawa/chainer,okuta/chainer,cupy/cupy,ktnyt/chainer,okuta/chainer,ysekky/chainer,aonotas/chainer,anaruse/chainer,tkerola/chainer,keisuke-umezawa/chainer