Update BoxDecoration and RenderParagraph to use sky.Color instead of int.

sky/examples/stocks2/lib/stock_app.dart

Index: sky/examples/stocks2/lib/stock_app.dart
diff --git a/sky/examples/stocks2/lib/stock_app.dart b/sky/examples/stocks2/lib/stock_app.dart
index 6f72f8cf331911496eb8e30affcdf79f790b6bad..1dd1c0a615184dcc7aa72fbe3c7fc8ecc5001809 100644
--- a/sky/examples/stocks2/lib/stock_app.dart
+++ b/sky/examples/stocks2/lib/stock_app.dart
@@ -209,7 +209,7 @@ class StocksApp extends App {
     return new Container(
       child: new BlockContainer(children: [buildToolBar()]),
       decoration: new BoxDecoration(
-        backgroundColor: 0xFFFFFFFF
+        backgroundColor: sky.Color.white
       )
     );