Fix error overlay 'Object.assign' issue in IE by including polyfills …

…before webpack client (#3046)

packages/react-scripts/config/webpack.config.dev.js

@@ -43,6 +43,8 @@ module.exports = {
   // The first two entry points enable "hot" CSS and auto-refreshes for JS.
   target: 'electron-renderer',
   entry: [
+    // We ship a few polyfills by default:
+    require.resolve('./polyfills'),
     // Include an alternative client for WebpackDevServer. A client's job is to
     // connect to WebpackDevServer by a socket and get notified about changes.
     // When you save a file, the client will either apply hot updates (in case
@@ -54,8 +56,6 @@ module.exports = {
     // require.resolve('webpack-dev-server/client') + '?/',
     // require.resolve('webpack/hot/dev-server'),
     require.resolve('react-dev-utils/webpackHotDevClient'),
-    // We ship a few polyfills by default:
-    require.resolve('./polyfills'),
     // Finally, this is your app's code:
     paths.appIndexJs,
     // We include the app code last so that if there is a runtime error during