Loosen Babel preset to use browserslist (#3770)

* Provide better defaults

* Let babel determine features to compile

* meh

* Remove setting of BABEL_ENV

* Revert "Remove setting of BABEL_ENV"

This reverts commit ee2db707faa8b9ada3e7a668e8a94944f5955a1e.

* Set browsers to ie9

packages/react-scripts/scripts/init.js

@@ -43,12 +43,12 @@ module.exports = function(
     eject: 'react-scripts eject',
   };
 
-  appPackage.browserslist = [
-    '>1%',
-    'last 4 versions',
-    'Firefox ESR',
-    'not ie < 9',
-  ];
+  appPackage.browserslist = {
+    development: ['chrome', 'firefox', 'edge'].map(
+      browser => `last 2 ${browser} versions`
+    ),
+    production: ['>1%', 'last 4 versions', 'Firefox ESR', 'not ie < 11'],
+  };
 
   fs.writeFileSync(
     path.join(appPath, 'package.json'),