title: babel-preset-env not transpiling arrow functions using webpack
body: <p>I'm using babel with webpack, I'm trying to make arrow functions work with Internet Explorer, but I can't get it working.</p>
  
  <p>This is my <em>package.json</em> dev dependencies:</p>
  
  <pre><code>"devDependencies": {
      "babel-core": "^6.26.3",
      "babel-loader": "^7.1.5",
      "babel-plugin-transform-class-properties": "^6.24.1",
      "babel-preset-env": "^1.7.0",
      "webpack": "^3.12.0",
      "webpack-cli": "^3.1.0"
    }
  </code></pre>
  
  <p>and this is my webpack.config.js:</p>
  
  <pre><code>module.exports = {
    entry: ['./chat.js'],
    devtool: 'source-map',
    output: {
      path: path.resolve(__dirname, "dist"),
      filename: "chat.js"
    },
    module: {
      rules: [
        {
          test: /\.js$/,
          loader: 'babel-loader',
          exclude: /node_modules/
        }
      ]
    }  
  };
  </code></pre>
  
  <p>I'm using the plugins with <em>.babelrc</em>:</p>
  
  <pre><code>{
    "presets": ["env"],
    "plugins": ["transform-class-properties"]
  }
  </code></pre>
  
  <p>I don't know what I'm doing wrong or if I'm missing something but I get the following syntax error on Internet Explorer:</p>
  
  <pre><code>DF.fn = () =&gt; {
          // Content
  };
  </code></pre>