Remove support for conflicting constructors.

tests/compiler/dart2js/simple_inferrer_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.
 
 import 'package:expect/expect.dart';
 import
     '../../../sdk/lib/_internal/compiler/implementation/types/types.dart'
     show TypeMask;
 
 import 'compiler_helper.dart';
@@ skipping 562 matching lines @@
   checkReturnInClass('B', 'returnInt1', typesInferrer.intType);
   checkReturnInClass('B', 'returnInt2', typesInferrer.intType);
   checkReturnInClass('B', 'returnInt3', typesInferrer.intType);
   checkReturnInClass('B', 'returnInt4', typesInferrer.intType);
   checkReturnInClass('B', 'returnInt5', typesInferrer.intType);
   checkReturnInClass('B', 'returnInt6', typesInferrer.intType);
   checkReturnInClass('B', 'returnInt7', typesInferrer.intType);
   checkReturnInClass('B', 'returnInt8', typesInferrer.intType);
   checkReturnInClass('B', 'returnInt9', typesInferrer.intType);
 
-  checkFactoryConstructor(String className) {
+  checkFactoryConstructor(String className, String factoryName) {
     var cls = findElement(compiler, className);
-    var element = cls.localLookup(buildSourceString(className));
+    var element = cls.localLookup(buildSourceString(factoryName));
     Expect.equals(new TypeMask.nonNullExact(cls.rawType),
                   typesInferrer.getReturnTypeOfElement(element));
   }
-  checkFactoryConstructor('A');
+  checkFactoryConstructor('A', '');
 }