Order GhostViews so that they display in their ghosted view's order.

Bug 17671834

GhostViews can be added in arbitrary order since they are added
depending on how they are insterted into the TransitionValues
maps. This CL does two things: it ensures that GhostViews are always
pulled to the top of the Overlay and inserts GhostViews into
the Overlay in the order that their ghosted views are drawn.

Change-Id: I9f68105126834cc8f30a6cfe5d58fc3c51465afd