build: Updating dependencies

composer:
* mediawiki/mediawiki-codesniffer: 34.0.0 → 35.0.0
* mediawiki/minus-x: 1.1.0 → 1.1.1

npm:
* eslint-config-wikimedia: 0.17.0 → 0.18.1

Additional changes:
* Removing manual extensions for eslint.

Change-Id: I986ee614ae25668d33c1aa3c5cb790352fb24c89

Gruntfile.js

@@ -11,7 +11,6 @@ module.exports = function ( grunt ) {
 		},
 		eslint: {
 			options: {
-				extensions: [ '.js', '.json' ],
 				cache: true
 			},
 			all: [