Bug 1375689 - Turn on experimentalObjectRestSpread in ESlint options. r=mossop

MozReview-Commit-ID: BLZp3HskBji

--HG--
extra : rebase_source : 721d0586deb572a5e989547d592d741cc9d15950

tools/lint/eslint/eslint-plugin-mozilla/lib/configs/recommended.js

@@ -57,6 +57,9 @@ module.exports = {
   },
 
   "parserOptions": {
+    "ecmaFeatures": {
+      "experimentalObjectRestSpread": true
+    },
     "ecmaVersion": 8
   },