[new compiler] Fix tst_qqmlvaluetypes

[new compiler] Fix tst_qqmlvaluetypes

* Make sure to remove earlier set bindings for any value type property, not just
  scripts. We want font.bold: false to also override an earlier actual binding
  for example.
* Propagate on assignments on qualified property names throughout the
  chain of bindings - that makes it easier to detect them early on.
* The group property collection in the bindings validator should only include
  value bindings to group properties, not on assignments - as they can always
  appear in parallel.

Change-Id: Ib7ec4de755a5a8d269324a77cba36eb945366274
Reviewed-by: Lars Knoll <lars.knoll@digia.com>