Remove support for interface in dart2js.

tests/language/constructor_name_test.dart

 // Copyright (c) 2013, 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.
 
-library spirodraw_test;
-
-import '../../../spirodraw/web/spirodraw.dart' as spirodraw;
-
-// @static-clean
-
-/**
- * This test exists to ensure that the spirodraw sample compiles without errors.
- */
-void main() {
-  
+class Foo {
+  Bar.Foo(); /// 01: compile-time error
+  factory Bar(); /// 02: compile-time error
+  factory Bar.Baz(); /// 03: compile-time error
 }
 
+
+void main() {
+  new Foo();
+  new Foo.Foo(); /// 01: continued
+  new Foo.Baz(); /// 03: continued
+}