**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

targetTable.set(event, target);
      currentTargetTable.set(event, currentTarget);
      listeners.depth++;
      for (var i = 0, len = listeners.length; i < len; i++) {
        var listener = listeners[i];
        if (listener.removed) {
          anyRemoved = true;
          continue;
        }
        if (listener.type !== type || !listener.capture && phase === CAPTURING_PHASE || listener.capture && phase === BUBBLING_PHASE) {
          continue;
        }
        try {
          if (typeof listener.handler === "function") listener.handler.call(currentTarget, event); else listener.handler.handleEvent(event);
          if (stopImmediatePropagationTable.get(event)) return false;
        } catch (ex) {
          if (!pendingError) pendingError = ex;
        }
      }
      listeners.depth--;
      if (anyRemoved && listeners.depth === 0) {
        var copy = listeners.slice();
        listeners.length = 0;
        for (var i = 0; i < copy.length; i++) {
          if (!copy[i].removed) listeners.push(copy[i]);
        }
      }
      return !stopPropagationTable.get(event);
    }
    function Listener(type, handler, capture) {