Recents transition fixes

- Make sure to destroy the saved surfaces while we resize a task. The
usual destroying mechanism doesn't work here because we don't add the
windows to WMS.mResizingWindows.
- Make sure not to save the surface when a resize happened after the
window has been marked as gone (exiting). In this case, we resize the
task, so we add the window to mResizingWindows, but then when we don't
layout the window because win.isGoneForLayout() == true, so it would
save a surface that has the wrong size.
- Ensure the configuration of the top task when dismissing the docked
stack. First, this speeds up when the user navigates to it in the
fullscreen stack. Second, it fixes some other weirdness with saving
surfaces.
- Only exclude windows from layout when hidden is requested, so when
transitioning from hidden -> shown, the app immediately gets the
updated size when the task was resized when the window was hidden.

Bug: 27276087
Change-Id: I6faf016724136d984b259d184af58d41684f3425