Turn on Babel helpers (facebook#5093)

* Turn on helpers and test importing something with async/await works

* Compiling babel runtime breaks itself

* Add helpers option to babel plugin with defaults

* Make helpers off by default and on in our configuration

* Hit eject and e2e

* meh

* copy'n'paste

* change again

* Turn off helpers by default in /prod, /dev, /test

* oops

* Spread undefined

* Use object assign not object spread

* Put preset in template since it's needed

* Fix e2e tests

Author: Timer

config/webpack.config.dev.js

@@ -275,6 +275,7 @@ module.exports = {
           // Unlike the application JS, we only compile the standard ES features.
           {
             test: /\.js$/,
+            exclude: /@babel\/runtime/,
             use: [
               // This loader parallelizes code compilation, it is optional but
               // improves compile time on larger projects
@@ -290,7 +291,10 @@ module.exports = {
                   babelrc: false,
                   compact: false,
                   presets: [
-                    require.resolve('babel-preset-react-app/dependencies'),
+                    [
+                      require.resolve('babel-preset-react-app/dependencies'),
+                      { helpers: true },
+                    ],
                   ],
                   cacheDirectory: true,
                   // Don't waste time on Gzipping the cache

config/webpack.config.prod.js

@@ -314,6 +314,7 @@ module.exports = {
           // Unlike the application JS, we only compile the standard ES features.
           {
             test: /\.js$/,
+            exclude: /@babel\/runtime/,
             use: [
               // This loader parallelizes code compilation, it is optional but
               // improves compile time on larger projects
@@ -324,7 +325,10 @@ module.exports = {
                   babelrc: false,
                   compact: false,
                   presets: [
-                    require.resolve('babel-preset-react-app/dependencies'),
+                    [
+                      require.resolve('babel-preset-react-app/dependencies'),
+                      { helpers: true },
+                    ],
                   ],
                   cacheDirectory: true,
                   // Save disk space when time isn't as important