Hi,
Changes on MobileFrontend have being merged deprecating jscs & jshint and instead using eslint.
See https://gerrit.wikimedia.org/r/#/c/320406/ and followup patches
This means there are some subtle changes to coding style, and more importantly that running grunt eslint:fix will now run eslint automatically fixing the code style issues in most cases.
Have a look at the patches to get a feel about the changes, and remember to update to master and re-run npm install to get the new tools ready.
Cheers.