chore(package): update uglify-js to version 2.6.2

http://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -38,7 +38,7 @@
     "mocha": "^2.1.0",
     "mocha-phantomjs": "^4.0.2",
     "standard": "^5.4.1",
-    "uglify-js": "^2.4.16"
+    "uglify-js": "^2.6.2"
   },
   "standard": {
     "global": [