title: react-dom blowing out webpack bundle size MASSIVELY
body: <p>This has got to be one of the strangest issues with webpack i have ever come across...  </p>
  
  <p>Check out this bundle breakdown:
  <a href="https://i.stack.imgur.com/obv7L.png" rel="noreferrer"><img src="https://i.stack.imgur.com/obv7L.png" alt="enter image description here"></a>
  react 116.01KB - fair enough</p>
  
  <p>react-dom 533.24KB - seriously WTF</p>
  
  <p>I thought it may be a corruption in my dependencies but nuking node_modules and reinstalling doesn't have any effect.  I guess it's something to do with the way webpack is bundling it but i'm lost for ideas.  The way i'm handing .js imports is pretty stock standard.</p>
  
  <pre><code>// webpack.config.js
  const path = require('path');
  // const BundleAnalyzerPlugin = require('webpack-bundle-analyzer').BundleAnalyzerPlugin;
  const ExtractTextPlugin = require('extract-text-webpack-plugin');
  const Dashboard = require('webpack-dashboard');
  const DashboardPlugin = require('webpack-dashboard/plugin');
  
  const dashboard = new Dashboard();
  
  module.exports = {
    context: path.join(__dirname, 'src'),
    entry: {
      bundle: './index.js',
    },
    output: {
      filename: 'bundle.js',
      path: path.join(__dirname, 'build'),
    },
    module: {
      rules: [
        {
          test: /\.html$/,
          use: 'file-loader?name=[name].[ext]',
        },
        {
          test: /.scss$/,
          use: ExtractTextPlugin.extract({
            fallback: 'style-loader',
            use: [
              'css-loader',
              'postcss-loader',
            ],
          }),
        },
        {
          test: /\.js$/,
          exclude: /node_modules/,
          use: 'babel-loader',
        },
      ],
    },
    plugins: [
      // new BundleAnalyzerPlugin(),
      new ExtractTextPlugin('styles.css'),
      new DashboardPlugin(dashboard.setData),
    ],
    devServer: {
      quiet: true,
    },
  };
  
  // .babelrc
  {
    "presets": [
      "react",
      "es2015"
    ],
    "plugins": ["transform-object-rest-spread"]
  }
  </code></pre>