Instead of applying a transform for every RenderObject, pass down an Offset for where to paint.

sky/sdk/lib/rendering/flex.dart

Index: sky/sdk/lib/rendering/flex.dart
diff --git a/sky/sdk/lib/rendering/flex.dart b/sky/sdk/lib/rendering/flex.dart
index 1bc8b8cd76d9e753086e177748007ad1ea8f67ae..084532a903f9844bcf83e41057b619101bc27e0d 100644
--- a/sky/sdk/lib/rendering/flex.dart
+++ b/sky/sdk/lib/rendering/flex.dart
@@ -394,7 +394,7 @@ class RenderFlex extends RenderBox with ContainerRenderObjectMixin<RenderBox, Fl
     defaultHitTestChildren(result, position: position);
   }
 
-  void paint(RenderCanvas canvas) {
-    defaultPaint(canvas);
+  void paint(RenderCanvas canvas, Offset offset) {
+    defaultPaint(canvas, offset);
   }
 }