tests: Update fn name to match id/class plurality

tests/page.js

@@ -115,7 +115,7 @@ module.exports = function Page(browser) {
 		return this.getActiveElement().getTagName();
 	};
 
-	this.getFocussedElementId = function () {
+	this.getFocussedElementName = function () {
 		return this.getActiveElement()
 			.getAttribute(!idSelectors ? 'id' : 'class');
 	};

tests/testOperations.js

@@ -22,7 +22,7 @@ function TestOperations(page) {
 	}
 
 	this.assertNewInputNotFocused = function () {
-		return page.getFocussedElementId()
+		return page.getFocussedElementName()
 			.then(function(name) {
 				assert.notEqual(name, 'new-todo');
 			});