Index: src/wp-includes/js/shortcode.js
===================================================================
--- src/wp-includes/js/shortcode.js	(revision 34907)
+++ src/wp-includes/js/shortcode.js	(working copy)
@@ -135,7 +135,7 @@
 			// 6. an unquoted value.
 			// 7. A numeric attribute in double quotes.
 			// 8. An unquoted numeric attribute.
-			pattern = /(\w+)\s*=\s*"([^"]*)"(?:\s|$)|(\w+)\s*=\s*\'([^\']*)\'(?:\s|$)|(\w+)\s*=\s*([^\s\'"]+)(?:\s|$)|"([^"]*)"(?:\s|$)|(\S+)(?:\s|$)/g;
+			pattern = /([\w-]+)\s*=\s*"([^"]*)"(?:\s|$)|([\w-]+)\s*=\s*\'([^\']*)\'(?:\s|$)|([\w-]+)\s*=\s*([^\s\'"]+)(?:\s|$)|"([^"]*)"(?:\s|$)|(\S+)(?:\s|$)/g;
 
 			// Map zero-width spaces to actual spaces.
 			text = text.replace( /[\u00a0\u200b]/g, ' ' );