fckeditor_process_textarea() bypasses Drupal's CSS processing, killing CSS aggregation and breaking LESS stylesheets in iframes

The editor's iframe accesses non-aggregated CSS and (where LESS stylesheets were being used with the less module), delivers unprocessed LESS source to the browser.

This can cause strange bugs which may come up just in Internet Explorer, such as the bullets and numbered list controls causing list items to float (and bullets to be hidden).

In the case of the project I just tracked this down on, this is because IE apparently gets more confused by the LESS source code; it interpreted a non-applicable (nested) li { float: left } rule as a global one.

Just reporting this bug so others may find it and perhaps know what the problem is without having to track it down like I did.