*feature*

>Warning: A component is `contentEditable` and contains `children` managed by React. It is now your responsibility to guarantee that none of those nodes are unexpectedly modified or duplicated. This is probably not intentional.

It would help heaps if I would know _which_ component is causing this.
var container = document.createElement('div');
      ReactDOM.render(<div foo={() => {}} />, container);
      expectDev(console.error.calls.count(0)).toBe(1);
      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
        'Warning: Invalid value for prop `foo` on <div> tag. Either remove it ' +
          'from the element, or pass a string or number value to keep ' +
          'it in the DOM. For details, see https://fb.me/react-attribute-behavior' +
          '\n    in div (at **)',
      );
    });
    it('should group multiple unknown prop warnings together', () => {
      spyOn(console, 'error');
      var container = document.createElement('div');
      ReactDOM.render(<div foo={() => {}} baz={() => {}} />, container);
      expectDev(console.error.calls.count(0)).toBe(1);
      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
        'Warning: Invalid values for props `foo`, `baz` on <div> tag. Either remove ' +
          'them from the element, or pass a string or number value to keep ' +
          'them in the DOM. For details, see https://fb.me/react-attribute-behavior' +
          '\n    in div (at **)',
      );
    });
    it('should warn for onDblClick prop', () => {
      spyOn(console, 'error');
      var container = document.createElement('div');
      ReactDOM.render(<div onDblClick={() => {}} />, container);
      expectDev(console.error.calls.count(0)).toBe(1);
      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
        'Warning: Invalid event handler property `onDblClick`. Did you mean `onDoubleClick`?\n    in div (at **)',
      );