chore(*): allow Node versions newer than 8; bump the minimum

Author: mgol

package.json

@@ -9,7 +9,7 @@
     "url": "https://github.com/angular/angular.js.git"
   },
   "engines": {
-    "node": "^8.9.1",
+    "node": ">=8.12.0",
     "yarn": ">=1.10.1",
     "grunt-cli": "^1.2.0"
   },