remove regenerator

package.json

@@ -45,7 +45,7 @@
     "prettier": "prettier --write --list-different .",
     "prettier:check": "prettier --check .",
     "check": "flow check",
-    "build": "rm -rf dist/* && babel src --ignore __tests__ --out-dir dist -b regenerator && npm run build:flow",
+    "build": "rm -rf dist/* && babel src --ignore __tests__ --out-dir dist && npm run build:flow",
     "build:flow": "find ./src -name '*.js' -not -path '*/__tests__*' | while read filepath; do cp $filepath `echo $filepath | sed 's/\\/src\\//\\/dist\\//g'`.flow; done",
     "watch": "node resources/watch.js",
     "preversion": "npm test",