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

sky/engine/core/painting/PictureRecorder.idl

Index: sky/engine/core/painting/PictureRecorder.idl
diff --git a/sky/engine/core/painting/PictureRecorder.idl b/sky/engine/core/painting/PictureRecorder.idl
index b1ea18510b980135bc66694d42e9bd76c926f779..2fc889de0273645bbe9d3fb3d1d42bfc7c9f337a 100644
--- a/sky/engine/core/painting/PictureRecorder.idl
+++ b/sky/engine/core/painting/PictureRecorder.idl
@@ -2,7 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 [
-    Constructor(double width, double height)
-] interface PictureRecorder : Canvas {
+  Constructor()
+] interface PictureRecorder {
+  readonly attribute boolean isRecording;
   Picture endRecording();
 };