Support default constructors in analyzer2dart.

pkg/analyzer2dart/test/tree_shaker_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'mock_sdk.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/source.dart';
@@ skipping 81 matching lines @@
 main() {
   var x = new A();
 }
 class A {}
 class B {}
 ''');
     helper.assertHasInstantiatedClass('A');
     helper.assertNoInstantiatedClass('B');
   });
 
+  test('Super class instantiation', () {
+    var helper = new TreeShakerTestHelper('''
+main() {
+  var x = new B();
+}
+class A {}
+class B extends A {}
+''');
+    helper.assertHasInstantiatedClass('A');
+    helper.assertHasInstantiatedClass('B');
+  });
+
   test('Method invocation', () {
     var helper = new TreeShakerTestHelper('''
 main() {
   var x = new A().foo();
 }
 class A {
   foo() {}
   bar() {}
 }
 class B {
@@ skipping 413 matching lines @@
   /**
    * Asserts that [world] doesn't contain a method with the given qualified
    * name.
    *
    * [qualifiedName] - the qualified name in form 'className.methodName'.
    */
   void assertNoMethod(String qualifiedName) {
     expect(methods, isNot(contains(qualifiedName)));
   }
 }