Refactor is.domElement to declare constants outside the function

test.js

@@ -9,6 +9,7 @@ const PromiseSubclassFixture = class extends Promise {};
 const ErrorSubclassFixture = class extends Error {};
 
 const document = jsdom();
+const createDomElement = el => document.createElement(el);
 
 const types = new Map([
 	['undefined', undefined],
@@ -93,12 +94,14 @@ const types = new Map([
 		new Object() // eslint-disable-line no-new-object
 	]],
 	['integer', 6],
-	['domElement', ['div',
+	['domElement', [
+		'div',
 		'input',
 		'span',
 		'img',
 		'canvas',
-		'script'].map(el => document.createElement(el))],
+		'script'
+	].map(createDomElement)],
 	['non-domElements', [
 		document.createTextNode('data'),
 		document.createProcessingInstruction('xml-stylesheet', 'href="mycss.css" type="text/css"'),