[Tizen][Runtime] Enable hosted app support on Tizen.

On Tizen, a web application use ```<tizen:content>``` to set entry page will be recognized as hosted app, and will cover the element ```<content>``` without  tizen namespace.This patch will enable this feature in Crosswalk
runtime.

BUG=XWALK-1492
Yes, Tizen core spec requires this, using tizen namespace in 'content' element represents a hosted app, otherwise, it's a packaged app.