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.

expect(element.ref).toBe('34');
    var expectation = {foo:'56'};
    Object.freeze(expectation);
    expect(element.props).toEqual(expectation);
  });
  it('coerces the key to a string', function() {
    var element = React.createFactory(ComponentClass)({
      key: 12,
      foo: '56',
    });
    expect(element.type).toBe(ComponentClass);
    expect(element.key).toBe('12');
    expect(element.ref).toBe(null);
    var expectation = {foo:'56'};
    Object.freeze(expectation);
    expect(element.props).toEqual(expectation);
  });
  it('preserves the owner on the element', function() {
    var Component = React.createFactory(ComponentClass);
    var element;
    var Wrapper = React.createClass({
      render: function() {
        element = Component();
        return element;
      },
    });
    var instance = ReactTestUtils.renderIntoDocument(
      React.createElement(Wrapper)
    );
    expect(element._owner.getPublicInstance()).toBe(instance);