Rename RenderCanvas to PaintingCanvas to avoid confusion with other classes that inherit from Rende…

sky/sdk/lib/rendering/paragraph.dart

Index: sky/sdk/lib/rendering/paragraph.dart
diff --git a/sky/sdk/lib/rendering/paragraph.dart b/sky/sdk/lib/rendering/paragraph.dart
index f118d0996fe36cf99748fddf352af03f4cdc7012..dcce468cb7b783e98bd4f8d105f4855f3581bd77 100644
--- a/sky/sdk/lib/rendering/paragraph.dart
+++ b/sky/sdk/lib/rendering/paragraph.dart
@@ -172,7 +172,7 @@ class RenderParagraph extends RenderBox {
                                           _applyFloatingPointHack(root.height)));
   }
 
-  void paint(RenderCanvas canvas, Offset offset) {
+  void paint(PaintingCanvas canvas, Offset offset) {
     // Ideally we could compute the min/max intrinsic width/height with a
     // non-destructive operation. However, currently, computing these values
     // will destroy state inside the layout root. If that happens, we need to