fixup! Implement Fullscreen API

fixup! Implement Fullscreen API

In tizen 2.4 environment, WRT calls the ewk_view_fullscreen_exit()
API and exits the event handler when pressing hardware back key
if it's fullscreen mode in only "Software key" mode or "windowed"
view mode.

However above two conditions(software key and windowed view modes)
were omitted in tizen 3.0, so the ewk_view_fullscreen_exit() API
was always called when pressing hardware back key in fullscreen mode.

This CL fixes these problem.

Bug: http://suprem.sec.samsung.net/jira/browse/TWF-3201

Change-Id: I4dda2d78be7af8cf75df72875aa2d7e94bbe2da9
Signed-off-by: Youngcheol Kang <ychul.kang@samsung.com>