Do not adjust child windows placement for fit to display.

Consider the case where we have made a child windows parent
and task smaller in the docked stack but the client has not
yet caught up and requested a new size for the child window.
In this case it is possible for the child windows requested
layout to extend beyond the bounds of the available display area
(in this case the containing frame). Our intended behavior is
to clip this extra area, while preserving the relative offset
of the child and parent window. If we apply gravity to fit within
the display frame, the behavior will instead be to modify
this offset in order to reduce the amount of cropped window.
While this is a sensible idea for laying out fullscreen tasks, it
is not helpful for windows layed out in the parent frame.

Bug: 27687126
Bug: 27676101
Bug: 27601572
Change-Id: I80607a29506dc5a127ac0eab12c2aeb9450e13f6