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

**What is the current behavior?**
The code is: 
```
class App extends React.Component {
  render() {
    return (
      <div>
        <sCript>alert('Hi');</sCript>
        <script>alert('script 2: this should not execute');</script>
      </div>
    );
  }
}
```
the script in ` <sCript>alert('Hi');</sCript>` executed.
![s_ 2018-10-11 15 56 00](https://user-images.githubusercontent.com/2378632/46789074-3a1ee500-cd6e-11e8-8b0f-1ab172857f7c.png)

**If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem. Your bug will get fixed much faster if we can run your code and it doesn't have dependencies other than React. Paste the link to your JSFiddle (https://jsfiddle.net/Luktwrdm/) or CodeSandbox (https://codesandbox.io/s/new) example below:**

Demo in codepen: https://codepen.io/zenany/pen/rqmPYq

**What is the expected behavior?**

`<sCript>alert('Hi');</sCript>` should not processed as code, this may cause security risk.

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

versions:
```
  "dependencies": {
    "react": "^16.5.2",
    "react-dom": "^16.5.2",
  },
```
browser: firefox, chrome


}
      }
      expect(() => {
        ReactDOM.render(<Component />, container);
      }).toErrorDev(
        "Warning: Using 'dangerouslySetInnerHTML' in an svg element with " +
          'Trusted Types enabled in an Internet Explorer will cause ' +
          'the trusted value to be converted to string. Assigning string ' +
          "to 'innerHTML' will throw an error if Trusted Types are enforced. " +
          "You can try to wrap your svg element inside a div and use 'dangerouslySetInnerHTML' " +
          'on the enclosing div instead.',
      );
      expect(container.innerHTML).toBe('<svg>unsafe html</svg>');
    });
  });
  it('should warn once when rendering script tag in jsx on client', () => {
    expect(() => {
      ReactDOM.render(<script>alert("I am not executed")</script>, container);
    }).toErrorDev(
      'Warning: Encountered a script tag while rendering React component. ' +
        'Scripts inside React components are never executed when rendering ' +
        'on the client. Consider using template tag instead ' +
        '(https://developer.mozilla.org/en-US/docs/Web/HTML/Element/template).\n' +
        '    in script (at **)',
    );
    
    ReactDOM.render(<script>alert("I am not executed")</script>, container);
  });
});