[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)
nit comment, `unsigned char* ` -> `unsigned char*` to follow the chromium coding style.