Changes made to To, Subject and Message content fields of PM are not saved if message contains hyperlink that was pressed from Preview mode (Firefox).

Steps to reproduce:

1. Login to forum as User
2. Go to User Menu ->Messages and press "Compose" button.
3. Fill out "To" and "Subject" fields with valid data.
4. Type some text that contains hyperlink in Message content field.
5. Press "Preview" button
6. Click on hyperlink from the Preview mode
7. Click on "Back" button on the browser's navigation toolbar
8. Overview To, Subject and Message content fields of the PM

Actual results:
To, Subject and Message content fields are empty
Expected results:
To, Subject and Message content fields should contain data that was present before Preview button was pressed.

Reproduced for Firefox. In Chrome data in Subject and Message content fields is saved and To field is also empty after Back button is pressed.