Limit node version to current LTS.

babel.config.js

@@ -24,7 +24,7 @@ module.exports = function(api) {
     case "production":
       // Config during builds before publish.
       envOpts.targets = {
-        node: 6,
+        node: "6.9",
       };
       break;
     case "development":

package.json

@@ -68,7 +68,7 @@
     "webpack-stream": "^4.0.0"
   },
   "engines": {
-    "node": ">= 6.x <= 9.x",
+    "node": ">= 6.9.0 <= 11.0.0-0",
     "npm": ">= 2.x <= 5.x",
     "yarn": ">=0.27.5 || >=1.0.0-20170811"
   },

packages/babel-core/package.json

@@ -22,6 +22,9 @@
     "babel-core",
     "compiler"
   ],
+  "engines": {
+    "node": ">=6.9.0 < 11.0.0-0"
+  },
   "browser": {
     "./lib/config/files/index.js": "./lib/config/files/index-browser.js",
     "./lib/transform-file.js": "./lib/transform-file-browser.js",