Commit 16fa186b63 attempted to fix the zoom animation problem
by throwing changes on the floor while the overview is animating. This has
the side effect that we might end up missing some positioning changes causes
windows to overlap the workspace thumbnails.
So revert those changes and fix it by simply by passing
WindowPositionFlags.ANIMATE during the overview animation.
This way the animation works as expected and we don't miss any position changes.
https://bugzilla.gnome.org/show_bug.cgi?id=703105
b1c936164c