src/third_party/web_platform_tests/conformance-checkers/html/attributes/lang/xmllang-same-isvalid.html - cobalt - Git at Google

 <!DOCTYPE html>
 <html xml:lang="en" lang="en">
 <head>
 <meta charset=utf-8>
 <title>When "xml:lang" is specified, the element must also have "lang" present with the same value</title>
 </head>
 <body>
 <p></p>
 </body>
 </html>
	<!DOCTYPE html>
	<html xml:lang="en" lang="en">
	<head>
	<meta charset=utf-8>
	<title>When "xml:lang" is specified, the element must also have "lang" present with the same value</title>
	</head>
	<body>
	<p></p>
	</body>
	</html>