Index: wp-includes/js/tinymce/plugins/wpfullscreen/editor_plugin_src.js
===================================================================
--- wp-includes/js/tinymce/plugins/wpfullscreen/editor_plugin_src.js	(revision 20709)
+++ wp-includes/js/tinymce/plugins/wpfullscreen/editor_plugin_src.js	(working copy)
@@ -141,7 +141,6 @@
 				ed.onChange.add(resize);
 				ed.onSetContent.add(resize);
 				ed.onPaste.add(resize);
-				ed.onKeyUp.add(resize);
 				ed.onPostRender.add(resize);
 
 				ed.getBody().style.overflowY = "hidden";