MER: Add packaging.
Add displayMarginBeginning/End to ListView and GridView.

This allows displaying content outside the visible area of
the view.

[ChangeLog][QtQuick] Add displayMarginBeginning/End to
ListView and GridView.

Change-Id: Idf9b5a0cd34a781c9603a9ad98ea189754972ba1
Reviewed-by: Alan Alpert (Personal) <416365416c@gmail.com>
Fix failing context->next != 0x1 assertion

After commit bf173fe5da381c88343296ca33ef6b06389c6d20 context objects are
always on the GC heap and no more in that special linked list or stack
allocated, so the next pointer became dangling/uninitialized and asserting on
it was bound to fail randomly.

Since we no more allocate contexts on the stack, we can safely remove the
assertion.

Task-number: QTBUG-35917
Change-Id: I104bd129c6c32f46a6302052f563abdf926cb879