Format property names consistently

package.json

@@ -8,6 +8,7 @@
   "dependencies": {
     "ast-types": "git+https://github.com/jlongster/ast-types.git",
     "babylon": "^6.15.0",
+    "esutils": "^2.0.2",
     "flow-parser": "^0.37.0",
     "minimist": "^1.2.0",
     "private": "^0.1.6",