Adds basic sprite sheet support to sprites

sky/tests/resources/display_list.dart

Index: sky/tests/resources/display_list.dart
diff --git a/sky/tests/resources/display_list.dart b/sky/tests/resources/display_list.dart
index a83f34d0aa9878ed6cdda5111169934f4510891c..3d98d1272b0e56401df5016fdca2e2d4d42ad86a 100644
--- a/sky/tests/resources/display_list.dart
+++ b/sky/tests/resources/display_list.dart
@@ -106,6 +106,10 @@ class TestDisplayList extends RenderObjectDisplayList {
     log("drawImage($image, $x, $y, $paint)");
   }
 
+  void drawImageRect(sky.Image image, sky.Rect src, sky.Rect dst, Paint paint) {
+    log("drawImageRect($image, $src, $dst, paint)");
+  }
+
   void paintChild(RenderObject child, Point position) {
     log("paintChild ${child.runtimeType} at $position");
     child.paint(new TestDisplayList(width, height, logger, indent: "$indent  |"));