build(babel): fix build and remove unused deps

use correct babelrc now that the library doesn't polyfill for older node versions and old browsers

.babelrc

@@ -1,8 +1,10 @@
 {
-  "presets": [
-    "@babel/preset-env"
-  ],
-  "plugins": [
-    "@babel/plugin-proposal-async-generator-functions"
-  ]
-}
+  "env": {
+    "production": {
+      "presets": ["@babel/preset-env"]
+    },
+    "test": {
+      "plugins": ["@babel/plugin-transform-modules-commonjs"]
+    }
+  }
+}

package.json

@@ -5,12 +5,12 @@
   "main": "dist/index.js",
   "scripts": {
     "prebuild": "rimraf dist",
-    "build": "npm-run-all build:*",
+    "build": "NODE_ENV=production npm-run-all build:*",
     "build:main": "babel src --out-dir dist --ignore src/*.test.js",
     "build:umd": "webpack --output-filename poll.umd.js -d",
     "build:umd.min": "webpack --output-filename poll.umd.min.js -p",
     "commit": "git cz",
-    "test": "mocha --require @babel/register src/*.test.js ",
+    "test": "jest src/*.test.js",
     "test:watch": "npm t -- -w",
     "semantic-release": "semantic-release",
     "travis-deploy-once": "travis-deploy-once",
@@ -39,14 +39,12 @@
   "homepage": "https://github.com/alivenotions/simple-poll#readme",
   "devDependencies": {
     "@babel/cli": "7.1.5",
-    "@babel/plugin-proposal-async-generator-functions": "7.1.0",
+    "@babel/plugin-transform-modules-commonjs": "7.7.5",
     "@babel/preset-env": "7.1.5",
-    "@babel/register": "7.0.0",
     "babel-loader": "8.0.4",
-    "chai": "4.2.0",
     "commitizen": "3.0.5",
     "cz-conventional-changelog": "2.1.0",
-    "mocha": "5.2.0",
+    "jest": "24.9.0",
     "node-fetch": "2.2.0",
     "npm-run-all": "4.1.5",
     "nyc": "13.3.0",