Bug 1411231 - Disable react/prefer-es6-class eslint option r=pbro

MozReview-Commit-ID: GR2fujyjw5j

--HG--
extra : rebase_source : f883d5bfcf03ef750a00ef4c7bd961fbda87f807

devtools/.eslintrc.js

@@ -57,7 +57,7 @@ module.exports = {
     "react/no-did-update-set-state": "error",
     "react/no-direct-mutation-state": "error",
     "react/no-unknown-property": "error",
-    "react/prefer-es6-class": ["error", "never"],
+    "react/prefer-es6-class": ["off", "always"],
     "react/prop-types": "error",
     "react/sort-comp": ["error", {
       order: [