Move rendering/RenderLayer* to layout/

LayoutTests/compositing/squashing/squashed-layer-loses-graphicslayer-expected.txt

-A squashing RenderLayer that becomes non-composited should correctly send a repaint invalidation to the new container GraphicsLayer that it paints into. When run interactively, hovering over the force-composited gray div should not cause other layers to disappear.
+A squashing Layer that becomes non-composited should correctly send a repaint invalidation to the new container GraphicsLayer that it paints into. When run interactively, hovering over the force-composited gray div should not cause other layers to disappear.
 
 CASE 1, original layer tree:
 {
   "bounds": [800, 600],
   "children": [
     {
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "children": [
@@ skipping 29 matching lines @@
       "repaintRects": [
         [300, 300, 100, 100],
         [220, 220, 100, 100],
         [140, 140, 100, 100],
         [60, 60, 100, 100]
       ]
     }
   ]
 }