async/await with webpack+babel

.babelrc

{
  "presets": ["es2015"],
  "plugins": ["transform-async-to-generator"]
}

index.js

async function foo() {
  console.log('async working!')
}

async function bar() {
  await foo()
  console.log('after foo')
}

bar()

package.json

{
  "name": "async-await",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "MIT",
  "devDependencies": {
    "babel-loader": "^6.2.2",
    "babel-plugin-transform-async-to-generator": "^6.5.0",
    "babel-polyfill": "^6.5.0",
    "babel-preset-es2015": "^6.5.0",
    "webpack": "^1.12.13"
  }
}

webpack.config.js

module.exports = {
  entry: ['babel-polyfill', './index.js'],
  output: {
    filename: 'bundle.js'
  },
  devtool: 'sourcemap',
  module: {
    loaders: [{
      test: /\.js?$/,
      exclude: /(node_modules)/,
      loader: 'babel'                                              
    }]
  }
}