[FIX] if only one div is empty in the subtitle body, subtitles were n…
Created by: nicosang
…ot displayed.
example :
<div region="r0"
<p xml:id="sub59000" begin="00:00:59.000" end="00:01:00.000" >
<span style="s2">eng : 00:00:59.000</span>
</p>
</div>
<div region="r0"/>