Refactoring to support dark theme better

sky/sdk/example/stocks/lib/main.dart

Index: sky/sdk/example/stocks/lib/main.dart
diff --git a/sky/sdk/example/stocks/lib/main.dart b/sky/sdk/example/stocks/lib/main.dart
index 8cf2f815e157391919207f3f7c1798b7ca142d29..b358f722c9e42deb53325f0e3271d5626f8f0210 100644
--- a/sky/sdk/example/stocks/lib/main.dart
+++ b/sky/sdk/example/stocks/lib/main.dart
@@ -68,15 +68,15 @@ class StocksApp extends App {
 
     ThemeData theme;
     if (optimismSetting == StockMode.optimistic) {
-      theme = new ThemeData.light(
-        primary: colors.Purple,
-        accent: colors.RedAccent,
-        darkToolbar: true
+      theme = new ThemeData(
+        brightness: ThemeBrightness.light,
+        primarySwatch: colors.Purple,
+        accentColor: colors.RedAccent[200]
       );
     } else {
-      theme = new ThemeData.dark(
-        primary: colors.Red,
-        accent: colors.PurpleAccent
+      theme = new ThemeData(
+        brightness: ThemeBrightness.dark,
+        accentColor: colors.RedAccent[200]
       );
     }