FEATURE: Re-instated broken link highlighting by manually checking all shortcodes in HtmlEditorField->Field(), and adding a class to broken ones.
From: Andrew Short <andrewjshort@gmail.com>
git-svn-id: svn://svn.silverstripe.com/silverstripe/open/modules/sapphire/trunk@88510 467b73ca-7a2a-4603-9d3b-597d59a354a9