When JSX is used, automatically import 'react' appropriately

Created by: jayphelps

Now if they use JSX, it will transparently import react and correctly reference the right createElement(). No more awkward import React from 'react';.

Before

import React from 'react';

const App = () => (
  <div>hello world</div>
);

export default App;

var _react = __webpack_require__(35);

var _react2 = _interopRequireDefault(_react);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

var App = function App() {
  return (0, _react.createElement)(
    'div',
    null,
    'hello world'
  );
};

exports.default = App;

After

const App = () => (
  <div>hello world</div>
);

export default App;

var _react = __webpack_require__(35);

var App = function App() {
  return (0, _react.createElement)(
    "div",
    null,
    "hello world"
  );
};

exports.default = App;

Anyone I show this ability to so instantly says "omg why didn't I use this earlier", so I imagine it is a welcome addition; but perhaps some will say it's "too much magic"...but let's be real, JSX is magic.

I could not find a test suite for create-react-app; I assume there isn't currently a test suite for the cli/scripts?