Cannot Load Multiple RTEs via AJAX
In the new frontend editing concept for 4.3, we're loading the RTE via AJAX and displaying it in a lightbox.
On the first load of the RTE, HTMLArea._editorEvent is created as a generic event handler. When the RTE is closed, the HTMLArea.cleanup() method is called to free many variables, including HTMLArea._editorEvent which is set to null. This causes problems with the second RTE load when HTMLArea has already been initialized but _editorEvent is now null rather than a true method.
The solution is to remove the null assignment in HTMLArea.cleanup(). At the same time, the null assignment for HTMLArea.onload can be removed also since it could cause similar issues.
(issue imported from #M10105)