Remove one more use of mirrors: Components now have to explicitly sync their fields.

sky/sdk/lib/framework/rendering/box.dart

Index: sky/sdk/lib/framework/rendering/box.dart
diff --git a/sky/sdk/lib/framework/rendering/box.dart b/sky/sdk/lib/framework/rendering/box.dart
index 0393554b5629863d423d4a55f05c4e6845f2e3f4..3db6b558fa25f93f5f9bb6764630aa70b3ea5790 100644
--- a/sky/sdk/lib/framework/rendering/box.dart
+++ b/sky/sdk/lib/framework/rendering/box.dart
@@ -797,7 +797,7 @@ class RenderDecoratedBox extends RenderProxyBox {
     assert(size.height != null);
 
     if (_decoration.backgroundColor != null || _decoration.boxShadow != null ||
-        _deocration.gradient != null) {
+        _decoration.gradient != null) {
       Rect rect = new Rect.fromLTRB(0.0, 0.0, size.width, size.height);
       if (_decoration.borderRadius == null)
         canvas.drawRect(rect, _backgroundPaint);