[Tizen][Desktop] Disable viewport meta

The apps using viewport meta are displayed wrongly
(not usable actually, see the related bug description).

Same problems observed with content shell on Linux.

This patch provides a temporary solution: disable viewport
meta tag.

BUG=XWALK-2577
Merge pull request #2446 from pozdnyakov/disable_viewport_meta

[Tizen][Desktop] Disable viewport meta