Pass the screen context directly to get_sample_permalink_html(). see #16379.

git-svn-id: https://develop.svn.wordpress.org/trunk@22129 602fd350-edb4-49c9-b593-d223f7449a82

wp-admin/js/sample-permalink.js

@@ -25,7 +25,7 @@ var editPermalink, makeSlugeditClickable;
 				post_id: post_id,
 				new_slug: new_slug,
 				new_title: $('#title').val(),
-				context: pagenow,
+				screen: pagenow,
 				samplepermalinknonce: $('#samplepermalinknonce').val()
 			}, function(data) {
 				$('#edit-slug-box').html(data);