an unnecessary argument in applyMiddleware.js

[HQidea]

Since there is no enhancer argument passed to an enhancer, so this argument can be omitted.

see: https://github.com/reactjs/redux/blob/master/src/applyMiddleware.js#L20

If this is ok, I'll send a pr later.

[jimbolla]

Duplicate: #2128 (comment)