Update eslint-config-wikimedia and lint (#112)

Update linting package and lint files.

Add .eslintcache to .gitignore

Author: mvolz

.gitignore

@@ -1,3 +1,4 @@
 coverage
 node_modules
 npm-debug.log
+.eslintcache

index.js

@@ -38,11 +38,12 @@ exports = module.exports = function ( urlOrOpts ) {
 		return BBPromise.reject( 'No uri supplied in argument' );
 	} else {
 		return BBPromise.resolve(
-			fetch( url, opts ).then( ( response ) => {
-				return response.text().then( ( body ) => {
-					return index.parseAll( cheerio.load( body ) );
-				} );
-			} )
+			// eslint-disable-next-line n/no-unsupported-features/node-builtins
+			fetch( url, opts ).then(
+				( response ) => response.text().then(
+					( body ) => index.parseAll( cheerio.load( body ) )
+				)
+			)
 		);
 	}
 };

lib/index.js

@@ -26,7 +26,7 @@ exports.parseAll = function ( chtml ) {
 	let key; // Key corresponding to location of result
 	return BBPromise.all( arr.map( ( x ) => x.reflect() ) )
 		.then( ( results ) => {
-			Object.keys( results ).forEach( function ( r ) {
+			Object.keys( results ).forEach( ( r ) => {
 				result = results[ r ];
 				key = keys[ r ];
 				if ( result && result.isFulfilled() && result.value() ) {