Remove qtjsbackend as dependency for qtdeclarative

This is the first step. The next step is to remove it from qtdeclarative's
sync.profile after this integrates.

Change-Id: Ice1424f3d01d8eb4082200900498bbb19392492b
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>