Upgrade eslint-config-wikimedia to 0.21.0

JavaScript code and comments changes:
* Remove no-multi-str disabling.
* Document $ parameter.
* Replace .substring() with .slice().
* Change assert.ok() to assert.strictEqual() in a test.

package.json

@@ -25,7 +25,7 @@
 		"Siebrand Mazeland"
 	],
 	"devDependencies": {
-		"eslint-config-wikimedia": "0.20.0",
+		"eslint-config-wikimedia": "0.21.0",
 		"eslint-plugin-html": "6.1.2",
 		"grunt": "1.4",
 		"grunt-contrib-qunit": "4.0.0",

src/jquery.uls.core.js

@@ -23,7 +23,6 @@
 	var template, ULS;
 
 	// Region numbers in id attributes also appear in the langdb.
-	// eslint-disable-next-line no-multi-str
 	template = '<div class="grid uls-menu"> \
 			<div id="search" class="row uls-search"> \
 				<div class="uls-search-wrapper"> \

src/jquery.uls.languagefilter.js

@@ -19,6 +19,8 @@
 /**
  * Usage: $( 'inputbox' ).languagefilter();
  * The values for autocompletion is from the options.languages or options.searchAPI.
+ *
+ * @param {jQuery} $
  */
 ( function ( $ ) {
 	'use strict';
@@ -270,12 +272,12 @@
 
 			userInput = this.$element.val();
 			suggestion = userInput +
-				languageName.substring( userInput.length, languageName.length );
+				languageName.slice( userInput.length, languageName.length );
 
 			if ( suggestion.toLowerCase() !== languageName.toLowerCase() ) {
 				// see if it was autonym match
 				autonym = $.uls.data.getAutonym( langCode ) || '';
-				suggestion = userInput + autonym.substring( userInput.length, autonym.length );
+				suggestion = userInput + autonym.slice( userInput.length, autonym.length );
 
 				if ( suggestion !== autonym ) {
 					// Give up. It may be an ISO/script code match.

src/jquery.uls.lcd.js

@@ -21,7 +21,6 @@
 ( function ( $ ) {
 	'use strict';
 
-	// eslint-disable-next-line no-multi-str
 	var noResultsTemplate = '<div class="uls-no-results-view"> \
 		<h2 data-i18n="uls-no-results-found" class="uls-no-results-found-title">No results found</h2> \
 		<div class="uls-no-results-suggestions"></div> \

test/jquery.uls.test.js

@@ -19,7 +19,7 @@
 	QUnit.module( 'jquery.uls' );
 
 	QUnit.test( '-- Initial check', function ( assert ) {
-		assert.ok( $.fn.uls, '$.fn.uls is defined' );
+		assert.strictEqual( typeof $.fn.uls, 'function', '$.fn.uls is a function' );
 	} );
 
 }( jQuery ) );