React 16 alpha allows returning array in render function but server renderer expects children to always be react elements

```
TypeError: Cannot read property 'toLowerCase' of undefined
    at ReactDOMServerRenderer.renderDOM
```

source
```javascript
function renderDOM(element, context) {
    var tag = element.type.toLowerCase(); // element is array
```

Fiddle: https://jsfiddle.net/84v837e9/160/

**react@16.0.0-alpha.13**
expect(e.value).toBe('Hello');
          
          e.value = 'Goodbye';
          ReactTestUtils.Simulate.change(e);
          expect(changeCount).toBe(1);
          expect(e.value).toBe('Goodbye');
        });
      });
      describe('user interaction with inputs before client render', function() {
        
        
        
        
        
        const testUserInteractionBeforeClientRender = async (
          element,
          initialValue = 'Hello',
          changedValue = 'Goodbye',
          valueKey = 'value',
        ) => {
          const field = await serverRender(element);
          expect(field[valueKey]).toBe(initialValue);
          
          field[valueKey] = changedValue;
          resetModules();
          
          const clientField = await renderIntoDom(element, field.parentNode);