bug 1065965 - Ensure save buttons enable when CKEditor source is edited.

Right now there's a warning because the attribute isn't on the textarea of CKEditor's source textarea.

To test:

1.  Go to the new document page
2.  Fill in *nothing*
3.  Click the "source" button of CKEditor
4.  Add some raw HTML
5.  See that the save buttons are enabled.