<!--
  Note: if the issue is about documentation or the website, please file it at:
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**Do you want to request a *feature* or report a *bug*?**

bug.

**What is the current behavior?**

```js
  renderer.create(
    <Fragment>
      <Fragment>foo</Fragment>
    </Fragment>
  )
  .toTree()
```

> Invariant Violation: toTree() does not yet know how to handle nodes with tag=10

https://codesandbox.io/s/olky92m01y

**What is the expected behavior?**

returns a tree.

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**

16.2.0

props: {},
    });
    renderer.update(<Component>{['Hi', 'Bye']}</Component>);
    expect(renderer.toJSON()).toEqual({
      type: 'div',
      children: ['Hi', 'Bye'],
      props: {},
    });
    renderer.update(<Component>Bye</Component>);
    expect(renderer.toJSON()).toEqual({
      type: 'div',
      children: ['Bye'],
      props: {},
    });
    renderer.update(<Component>{42}</Component>);
    expect(renderer.toJSON()).toEqual({
      type: 'div',
      children: ['42'],
      props: {},
    });
    renderer.update(
      <Component>
        <div />
      </Component>,
    );
    expect(renderer.toJSON()).toEqual({
      type: 'div',
      children: [
        {
          type: 'div',