[Tizen] Fixed screen displayed abnormally when playing some size of html5 mp4 videos.

[Tizen] Fixed screen displayed abnormally when playing some size of html5 mp4 videos.

BUG=XWALK-1781 (https://crosswalk-project.org/jira/browse/XWALK-1781)
Sorry that I'm not so clear last time. I meant the comment at end is kind of strange, I'd suggest comment them as whole para before the code block.