Fix docstring of FunctionTestCase
Fix docstring of FunctionTestCase

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