Avoid keeping a RWHVDelegate pointer in WebContentsViewQt.

There can be multiple RWHVDelegates within one WebContentsViewQt
during navigation. Avoid keeping a pointer by sending the focus
call to the client directly, which fits the purpose better.

Change-Id: I863c174e9a2567f3580f3cb525bc5353ab2a4417
Reviewed-by: Zeno Albisser <zeno.albisser@digia.com>
Simplify the ownership between RWHVQt and RWHVQtDelegate.

Let the RWHVQt explicitly own its delegate.
Keep the same behavior by letting RWHVQt::Destroy delete itself directly
like done in RWHVGtk instead of deleting the RWHVDelegate which would
then delete its RWHV.

Change-Id: I051c95d608964ebcd66d3ccbe728f63c0ca397ae
Reviewed-by: Zeno Albisser <zeno.albisser@digia.com>
Delay the RWHVDelegate parenting until it's been attached to its RWHV.

This avoids the RWHV being accessed before being attached to
the delegate when attaching the later to the view's layout.

Change-Id: I5fffef60fdd7203cfb4ced807b5475aac676ea09
Reviewed-by: Zeno Albisser <zeno.albisser@digia.com>