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.

getDefaultProps: function() {
        return {prop: 'testKey'};
      },
      render: function() {
        return <span />;
      },
    });
    var instance = React.createElement(Component);
    var clonedInstance = React.cloneElement(instance, {prop: undefined});
    expect(clonedInstance.props.prop).toBe('testKey');
    var clonedInstance2 = React.cloneElement(instance, {prop: null});
    expect(clonedInstance2.props.prop).toBe(null);
    var instance2 = React.createElement(Component, {prop: 'newTestKey'});
    var cloneInstance3 = React.cloneElement(instance2, {prop: undefined});
    expect(cloneInstance3.props.prop).toBe('testKey');
    var cloneInstance4 = React.cloneElement(instance2, {});
    expect(cloneInstance4.props.prop).toBe('newTestKey');
  });
  it('throws when changing a prop (in dev) after element creation', function() {
    var Outer = React.createClass({
      render: function() {
        var el = <div className="moo" />;
        expect(function() {
          el.props.className = 'quack';
        }).toThrow();
        expect(el.props.className).toBe('moo');
        return el;
      },
    });
    var outer = ReactTestUtils.renderIntoDocument(<Outer color="orange" />);