BUG Trigger TinyMCE onChange more frequently

Periodically check for inline changes when focused,
since TinyMCE's onChange only fires on certain actions
like inserting a new paragraph, as opposed to any user input.

This also works around an issue where the "save" button
wouldn't trigger if the click is the cause of a "blur" event
after an (undetected) inline change. This "blur" causes onChange
to trigger, which will change the button markup to show "alternative" styles,
effectively cancelling the original click event.

To reproduce that save button behaviour, simply open an edit form in the CMS,
and type a new character anywhere in the existing text (without using the editor buttons or linebreaks).
The change detection won't trigger. A direct click from there on the "save" button will NOT trigger a save.

Tested in Chrome and IE8