add babel plugins to provide spread operations & destructuring

.babelrc

@@ -1,6 +1,7 @@
 {
   "presets": [
     [
+      // Latest stable ECMAScript features
       "@babel/preset-env",
       {
         "targets": {
@@ -12,9 +13,15 @@
     ]
   ],
   "plugins": [
+    // Some transforms (such as object-rest-spread)
+    // don't work without it: https://github.com/babel/babel/issues/7215
+    ["@babel/plugin-transform-destructuring", { "useBuiltIns": true }],
+    ["@babel/plugin-proposal-object-rest-spread", { "useBuiltIns": true }],
     [
+      // Polyfills the runtime needed for async/await and generators
       "@babel/plugin-transform-runtime",
       {
+        "helpers": false,
         "regenerator": true
       }
     ]

package.json

@@ -20,6 +20,8 @@
   },
   "devDependencies": {
     "@babel/core": "^7.6.4",
+    "@babel/plugin-proposal-object-rest-spread": "^7.6.2",
+    "@babel/plugin-transform-destructuring": "^7.6.0",
     "@babel/plugin-transform-runtime": "^7.6.2",
     "@babel/preset-env": "^7.6.3",
     "autoprefixer": "^9.7.0",