The error event on `<source>` elements doesn't work. Looking at #4370, it seems like there is an `onError` for `<video>` but I can't tell if that's supposed to work for `<source>` too.

The error event is useful so I can deduce which format the browser is using.

}).toThrowError(
        'menuitem is a void element tag and must not have `children` or use ' +
        '`props.dangerouslySetInnerHTML`.'
      );
    });
    it('should validate against multiple children props', function() {
      expect(function() {
        mountComponent({children: '', dangerouslySetInnerHTML: ''});
      }).toThrowError(
        'Can only set one of `children` or `props.dangerouslySetInnerHTML`.'
      );
    });
    it('should validate against use of innerHTML', function() {
      spyOn(console, 'error');
      mountComponent({innerHTML: '<span>Hi Jim!</span>'});
      expect(console.error.calls.count()).toBe(1);
      expect(console.error.calls.argsFor(0)[0]).toContain(
        'Directly setting property `innerHTML` is not permitted. '
      );
    });
    it('should validate use of dangerouslySetInnerHTML', function() {
      expect(function() {
        mountComponent({dangerouslySetInnerHTML: '<span>Hi Jim!</span>'});
      }).toThrowError(
        '`props.dangerouslySetInnerHTML` must be in the form `{__html: ...}`. ' +
        'Please visit https://fb.me/react-invariant-dangerously-set-inner-html for more information.'
      );
    });
    it('should validate use of dangerouslySetInnerHTML', function() {
      expect(function() {