Resolve type names inside guard property of SignalTransition

SignalTransition's guard is evaluated against ad-hoc QQmlContext because
it needs signal args added to its contextProperty.
Since QQmlContext created this way does not have import type cache, we
could not use type names inside guard.
To avoid this problem, this patch makes guard's context inherit parent's
type cahce.

Change-Id: I4ddd559779681b53d4ee42f4820d05438addb5ac
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>
Add files generated by tests to gitignore

Change-Id: I1fac4df1e00cbe37c0c9ea69562dffc1eb4d5111
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>