test/xhtmlcomp - third_party/libxml2 - Git at Google

 <?xml version="1.0"?>
 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
 <html>
   <body>
     <h1><abbr>a</abbr> b</h1>
   </body>
 </html>
	<?xml version="1.0"?>
	<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
	"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
	<html>
	<body>
	<h1><abbr>a</abbr> b</h1>
	</body>
	</html>