Fix elementary widget stacking

Fix elementary widget stacking

The problem could be observed by showing extra actions menu in ubrowser
(rightmost button in the navigation bar). When shown large part of the
menu would be improperly stacked below the webview widget.

The root cause was in the fact that after the refactoring branch changes
both the NativeView and ContentNativeView widgets were not added to the
view smart object. This patch fixes that.

Change-Id: I38213ba03c1b08feb0643f661f063e1c530fc78f
Signed-off-by: Piotr Tworek <p.tworek@samsung.com>