Support top-level field declaration and assignment in analyzer2dart.

pkg/analyzer2dart/lib/src/modely.dart

Index: pkg/analyzer2dart/lib/src/modely.dart
diff --git a/pkg/analyzer2dart/lib/src/modely.dart b/pkg/analyzer2dart/lib/src/modely.dart
index 69c5fc7786cc454741edf8097cec96162f658114..fd144258e51c0475f00693b5612ad6f4c87967de 100644
--- a/pkg/analyzer2dart/lib/src/modely.dart
+++ b/pkg/analyzer2dart/lib/src/modely.dart
@@ -700,6 +700,12 @@ class TopLevelVariableElementY extends ElementY
   @override
   dart2js.DartType get type => converter.convertType(element.type);
 
+  @override
+  bool get isFinal => element.isFinal;
+
+  @override
+  bool get isConst => element.isConst;
+
   TopLevelVariableElementY(ElementConverter converter,
                            analyzer.TopLevelVariableElement element)
       : super(converter, element);