babel es2015 -> env

Author: maxwellbenton

package.json

@@ -23,6 +23,7 @@
   "homepage": "https://github.com/learn-co-curriculum/java-script-arithmetic-lab#readme",
   "devDependencies": {
     "babel-core": "^6.11.4",
+    "babel-preset-env": "^1.7.0",
     "babel-preset-es2015": "^6.9.0",
     "expect": "^1.20.2",
     "jsdom": "^9.2.1",

test/root.js

@@ -7,7 +7,7 @@ const path = require('path');
 
 before(function(done) {
   const babelResult = babel.transformFileSync(path.resolve(__dirname, '..', 'index.js'), {
-    presets: ['es2015']
+    presets: ['env']
   });
 
   //const src = path.resolve(__dirname, '..', 'index.js');