Bug 1405279 - Lint for unused variables. r=whimboo

MozReview-Commit-ID: 6hUMzC21Tl

--HG--
extra : rebase_source : 64943c3d934674066abf385035db1949c1a71891

testing/marionette/.eslintrc.js

@@ -17,6 +17,7 @@ module.exports = {
     "no-fallthrough": "error",
     "no-new-object": "error",
     "no-undef-init": "error",
+    "no-unused-vars": ["error", {}],
     "no-var": "error",
     "object-curly-spacing": ["error", "never"],
     "semi": "error",