Merge pull request #219 from mozilla/greenkeeper-isparta-3.5.3

Update isparta to version 3.5.3 🚀

package.json

@@ -38,7 +38,7 @@
     "grunt-jscs": "2.1.0",
     "grunt-mocha-test": "0.12.7",
     "grunt-webpack": "1.0.11",
-    "isparta": "3.1.0",
+    "isparta": "3.5.3",
     "json-loader": "0.5.3",
     "load-grunt-configs": "0.4.3",
     "load-grunt-tasks": "3.3.0",