[1.19] Wrong path to CSS override in WYSIWYG editor

CSS override path is incorrect in the head of the iframe for the wysiwyg editor.

The path is written as "/public://5327b48025c4e444255aa85fe33bc43255630e3e547ee_platon_override.css" for CKeditor.

For the TinyMCE editor, it is written as "http://dev.mylanguagesoup.com/public://5327b48025c4e444255aa85fe33bc4325..."

In both cases, the protocol "public://" is not being converted to the system file path.