Decouple Canvas from DisplayList and map Picture and PictureRecorder more directly to their Skia co…

sky/sdk/lib/rendering/object.dart

Index: sky/sdk/lib/rendering/object.dart
diff --git a/sky/sdk/lib/rendering/object.dart b/sky/sdk/lib/rendering/object.dart
index 998bea32935f69fb34b7c1e0011c86776099e2b0..bc100a77d188ba23c0d543651a0da22a6e10c093 100644
--- a/sky/sdk/lib/rendering/object.dart
+++ b/sky/sdk/lib/rendering/object.dart
@@ -26,10 +26,9 @@ class ParentData {
   String toString() => '<none>';
 }
 
-const kLayoutDirections = 4;
+class RenderCanvas extends sky.Canvas {
+  RenderCanvas(sky.PictureRecorder recorder, double width, double height) : super(recorder, width, height);
 
-class RenderObjectDisplayList extends sky.PictureRecorder {
-  RenderObjectDisplayList(double width, double height) : super(width, height);
   void paintChild(RenderObject child, Point position) {
     translate(position.x, position.y);
     child.paint(this);
@@ -219,7 +218,7 @@ abstract class RenderObject extends AbstractNode implements HitTestTarget {
     assert(!debugDoingPaint);
     scheduler.ensureVisualUpdate();
   }
-  void paint(RenderObjectDisplayList canvas) { }
+  void paint(RenderCanvas canvas) { }
 
 
   // EVENTS