fix(package): update babylon to version 7.0.0-beta.31

Author: greenkeeper[bot]

package.json

@@ -62,7 +62,7 @@
   "dependencies": {
     "astq": "^2.0.2",
     "babel-generator": "^6.24.1",
-    "babylon": "7.0.0-beta.9",
+    "babylon": "7.0.0-beta.31",
     "chalk": "^2.3.0",
     "dts-dom": "^0.1.20",
     "get-stdin": "^5.0.1",