[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
nit, prefer `return source.empty() ? GURL() : data->GetResourceURL(source);`