**Do you want to request a _feature_ or report a _bug_?**
feature ( I guess? )

**What is the current behavior?**
React doesn't support `slot` attribute which comes with shadowDom v1, so it will throw error and because of that, web component isn't working

code:

``` js
class App extends Component {
  render() {
    return (
      <div className="App">
        <div className="App-header">
          <img src={logo} className="App-logo" alt="logo" />
          <h2>Welcome to React</h2>
        </div>
        <p className="App-intro">
          To get started, edit <code>src/App.js</code> and save to reload.
        </p>
        <div>
          <fancy-tabs background hello="World!">
            <button slot="title">Tab 1</button>
            <button slot="title" selected>Tab 2</button>
            <button slot="title">Tab 3</button>
            <section>content panel 1</section>
            <section>content panel 2</section>
            <section>content panel 3</section>
          </fancy-tabs>
        </div>
      </div>
    );
  }
}
```

rendered html with error

<img width="919" alt="screen shot 2016-09-21 at 2 05 47 pm" src="https://cloud.githubusercontent.com/assets/1223799/18717136/4d2fe7d2-801f-11e6-8205-795576144626.png">

**If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem via https://jsfiddle.net or similar (template: https://jsfiddle.net/reactjs/69z2wepo/).**

**What is the expected behavior?**

Support new DOM attribute standard

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

React 15.3.2 / Chrome 53 / OSX El Capitan

render() {
          return <table>{this.props.children}</table>;
        }
      }
      class FancyTable extends React.Component {
        render() {
          return <Table>{this.props.children}</Table>;
        }
      }
      var Viz1 = React.createClass({
        render: () => <table><FancyRow /></table>,
      });
      var App1 = React.createClass({
        render: () => <Viz1 />,
      });
      ReactTestUtils.renderIntoDocument(<App1 />);
      expect(console.error.calls.count()).toBe(1);