dart2dart support for instantiatin simple top-level class:

tests/compiler/dart2js/unparser_test.dart

Index: tests/compiler/dart2js/unparser_test.dart
diff --git a/tests/compiler/dart2js/unparser_test.dart b/tests/compiler/dart2js/unparser_test.dart
index 523d0c96a7e6ca735a017fc2aa0810eb27b7a720..184b4d448484f31fbd50de93a0ce5dac1c5a71e7 100644
--- a/tests/compiler/dart2js/unparser_test.dart
+++ b/tests/compiler/dart2js/unparser_test.dart
@@ -19,7 +19,7 @@ testUnparseMember(String member) {
 
 final coreLib = @'''
 #library('corelib');
-interface Object {}
+class Object {}
 interface bool {}
 interface num {}
 interface int extends num {}
@@ -127,6 +127,11 @@ testSimpleObjectInstantiation() {
   testUnparse('main(){new Object();}');
 }
 
+testSimpleTopLevelClass() {
+  final src = 'main(){new A();}class A{A(){}}';
+  testDart2Dart(src, (String s) => Expect.equals(src, s));
+}
+
 main() {
   testGenericTypes();
   testForLoop();
@@ -138,5 +143,6 @@ main() {
   testConstModifier();
   testSimpleFileUnparse();
   testSimpleObjectInstantiation();
+  testSimpleTopLevelClass();
   testTopLevelField();
 }