This is a bug in `React.createElement` code:

`React.createElement` does not warn if `props.__proto__` is null ( from `Object.create(null)` ) since it [believes that to be a plain object](https://github.com/facebook/react/blob/master/src/isomorphic/classic/element/ReactElement.js#L135) originating from #6134. But since it directly accesses `hasOwnProperty` it fails if such object is passed as props.

Reproduce:

``` js
const props = Object.create(null);
React.createElement(() => null, props);
```

**What is the expected behavior?**
It shouldn't use `hasOwnProperty` directly on props if such object is expected.

React: 15.1.0
Browsers: All
OS: All

This affects all versions of React but since after 15.1.0 the acceptable shape of props is explicitly defined then it should be explicitly supported as well.

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