Fix crash in various qqmlbuiltinfunctions

These functions use QV8Engine::callingContext(), which relies on QV4::ExecutionEngine::qmlContextObject()
to retrieve the correct QML context. That function relies on outer, which isn't set for the SimpleCallContext
objects we set up.

Added a quirk to start the outer traversal with the parent if the current context is a SimpleCallContext.

Change-Id: Iebc3a6b68c9966ad7278a05bf37a6fb55523bff4
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Fix uninitialized reads during GC

Make sure to initialize both setter and getter fields for accessors

Change-Id: Ic1187da9e97694e58d4dd7634988dabd55b0700b
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Cleanup handlReferenceManagement auto test

Replace the vtable hacks with a simple property to maintain a GC visible
object reference.

Change-Id: Iae178d59dac23114353c152ef86224c9373a6025
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Fix crashes in some worker threads auto tests

Replace the crashing use of QV4::ExecutionEngine::publicEngine from within
worker threads (null pointer there) with direct pass-through of the QQmlEngine
pointer. It will be null within worker threads, but that the code can handle.

Change-Id: I8eff9d2cc6ca6f2afd9c0eef203975be9119b9b6
Reviewed-by: Lars Knoll <lars.knoll@digia.com>