Index: src/wp-includes/js/wplink.js
===================================================================
--- src/wp-includes/js/wplink.js	(revision 32702)
+++ src/wp-includes/js/wplink.js	(working copy)
@@ -356,6 +356,10 @@
 			link = getLink();
 			text = inputs.text.val();
 
+			if ( '' === text ) {
+				text = attrs.href;
+			}
+
 			if ( link ) {
 				if ( text ) {
 					if ( 'innerText' in link ) {