Index: src/wp-includes/js/shortcode.js
===================================================================
--- src/wp-includes/js/shortcode.js	(revision 38065)
+++ src/wp-includes/js/shortcode.js	(working copy)
@@ -326,11 +326,6 @@
 			_.each( options.attrs, function( value, attr ) {
 				text += ' ' + attr;
 
-				// Use empty attribute notation where possible.
-				if ( '' === value ) {
-					return;
-				}
-
 				// Convert boolean values to strings.
 				if ( _.isBoolean( value ) ) {
 					value = value ? 'true' : 'false';