bump uglify-js to ^2.8.12

Author: etpinard

package.json

@@ -131,7 +131,7 @@
     "read-last-lines": "^1.1.0",
     "requirejs": "^2.3.1",
     "through2": "^2.0.3",
-    "uglify-js": "^2.8.8",
+    "uglify-js": "^2.8.12",
     "watchify": "^3.9.0",
     "xml2js": "^0.4.16"
   }