DOM-less stocks app shouldn't crash on touch

sky/sdk/lib/framework/components2/scaffold.dart

Index: sky/sdk/lib/framework/components2/scaffold.dart
diff --git a/sky/sdk/lib/framework/components2/scaffold.dart b/sky/sdk/lib/framework/components2/scaffold.dart
index bbc7ba78d40d76aec8553fd2f4b8aa0ef875ded2..078e5eb5b1996617582ded5502ee08e182ec7e2f 100644
--- a/sky/sdk/lib/framework/components2/scaffold.dart
+++ b/sky/sdk/lib/framework/components2/scaffold.dart
@@ -148,7 +148,7 @@ class RenderScaffold extends RenderDecoratedBox {
 
   void hitTestChildren(HitTestResult result, { double x, double y }) {
     assert(floatingActionButton == null || floatingActionButton.parentData is BoxParentData);
-    assert(statusBar == null || statusBar.parentData is BoxParentData);
+    assert(statusbar == null || statusbar.parentData is BoxParentData);
     if ((drawer != null) && (x < drawer.width)) {
       drawer.hitTest(result, x: x, y: y);
     } else if ((floatingActionButton != null) && (x >= floatingActionButton.parentData.x) && (x < floatingActionButton.parentData.x + floatingActionButton.width)
@@ -158,7 +158,7 @@ class RenderScaffold extends RenderDecoratedBox {
       toolbar.hitTest(result, x: x, y: y);
     } else if ((statusbar != null) && (y > statusbar.parentData.y)) {
       statusbar.hitTest(result, x: x, y: y-statusbar.parentData.y);
-    } else {
+    } else if (body != null) {
       body.hitTest(result, x: x, y: y-body.parentData.y);
     }
   }