**Do you want to request a *feature* or report a *bug*?**
bug

**What is the current behavior?**
React 15.x was able to render within a DocumentFragment/shadowRoot, not possible with Fiber anymore

**DEMO**

https://www.webpackbin.com/bins/-KvPFG7-HGfQ34IgUxQt

```js
import React, {Component} from 'react'
import {render} from 'react-dom'


class MyComponent extends Component{
  render(){
    return <div>Hello From React !</div>
  }
}

class MyElement extends HTMLElement {
  static is = 'my-element'
  constructor(){
    super()
    const shadowRoot = this.attachShadow({mode:'open'})
    try {
      // this fails 
      render(<MyComponent/>, shadowRoot)
    } catch (e){
      console.error(e)
      shadowRoot.innerHTML = `
        <div style="color:red;">${e}</div>
        <div>see console log for stack trace</div>
       `
    }
  }
  connectedCallback(){
    console.log('MyElement mounted!')
  }
}

customElements.define(MyElement.is, MyElement)
```


related -> https://github.com/skatejs/renderer-react/issues/3

**What is the expected behavior?**
be able to render to shadow root like previous versions of React

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**
React 16
Chrome

var remNodes = [];
        var s = "";
        var modNode;
        for (var i = 0, n; i < nodes.length; i++) {
          n = nodes[i];
          if (n.nodeType === Node.TEXT_NODE) {
            if (!modNode && !n.data.length) this.removeNode(n); else if (!modNode) modNode = n; else {
              s += n.data;
              remNodes.push(n);
            }
          } else {
            if (modNode && remNodes.length) {
              modNode.data += s;
              cleanupNodes(remNodes);
            }
            remNodes = [];
            s = "";
            modNode = null;
            if (n.childNodes.length) n.normalize();
          }
        }
        if (modNode && remNodes.length) {
          modNode.data += s;
          cleanupNodes(remNodes);
        }
      }
    });
    defineWrapGetter(Node, "ownerDocument");
    registerWrapper(OriginalNode, Node, document.createDocumentFragment());
    delete Node.prototype.querySelector;