BUG: Fixes #2796 XSS filtering off edit/close links

This is a fix for issue #2796 where the recent 2.4 security fixes have broken the Edit/Close links on the ComplexTableField popup message.
The issue can be replicated by going to File & Images in the CMS backend clicking on the edit icon next to a file to bring up the popup box and clicking save.
This patch resolves this issue.

It has been tested on Chrome, FireFox, Safari and IE9.

I have also noticed that the Popups for ComplexTableField has other broken functionality for example the edit link in the popup goes to a blank page this patch does not resolve this issue and I will raise another issue for this