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

sky/sdk/lib/widgets/ink_well.dart

Index: sky/sdk/lib/widgets/ink_well.dart
diff --git a/sky/sdk/lib/widgets/ink_well.dart b/sky/sdk/lib/widgets/ink_well.dart
index 4d33f1fc27bfaccea2e90f8ac0b41d5eb5706686..d00530d1f2bbc4d878288ecfd058c36aab4aec25 100644
--- a/sky/sdk/lib/widgets/ink_well.dart
+++ b/sky/sdk/lib/widgets/ink_well.dart
@@ -52,7 +52,7 @@ class InkSplash {
     well.markNeedsPaint();
   }
 
-  void paint(RenderCanvas canvas) {
+  void paint(PaintingCanvas canvas) {
     int opacity = (_kSplashInitialOpacity * (1.0 - (_radius.value / _targetRadius))).floor();
     sky.Paint paint = new sky.Paint()..color = new sky.Color(opacity << 24);
     canvas.drawCircle(position, _radius.value, paint);
@@ -88,7 +88,7 @@ class RenderInkWell extends RenderProxyBox {
     markNeedsPaint();
   }
 
-  void paint(RenderCanvas canvas, Offset offset) {
+  void paint(PaintingCanvas canvas, Offset offset) {
     if (!_splashes.isEmpty) {
       canvas.save();
       canvas.translate(offset.dx, offset.dy);