Update dependency uglify-js to v3.8.0 (#13524)

Co-authored-by: WhiteSource Renovate <renovatebot@gmail.com>

package.json

@@ -20,7 +20,7 @@
     "less": "3.11.1",
     "source-map": "0.7.3",
     "timeago": "1.6.7",
-    "uglify-js": "3.7.7",
+    "uglify-js": "3.8.0",
     "underscore": "1.9.2"
   },
   "devDependencies": {}