[RAL] Make sure RenderLayers are invalidated when moved.

With Repaint-After-Layout we have to make sure that as
layers are moved around we properly invalidate the old
and new positions. To do this, I've updated the
updateLayerPositions call to check if the previous and
new repaint container offsets have changed. If so, I mark
the object as needing invalidation.

In order to not have an n^2 tree walk for each containerForRepaint()
call I'm passing the repaint container down the tree as we
recurse through updateLayerPositions.

BUG=371640

Review URL: https://codereview.chromium.org/285103003

git-svn-id: svn://svn.chromium.org/blink/trunk@175388 bbb929c8-8fbe-4397-9dbb-9b2b20218538