PDF Export content is not properly displayed in Firefox 39

1. Export any page in PDF format.
2. Tick all the checkboxes (cover, table of contentes, comments, image attachments).
3. Click Export.
4. The page is displayed in a PFD format, but without the text content. The text exists in the page, but is not visible. You can see this fact selecting with the mouse the blank space from the page, where the text content was supposed to be.
5. The users image is maximized.

PS: This test didn`t pass only on Mozilla 39.
On Mozilla 40 and Chrome 44, the PDF page is displayed correctly.