Remove support for conflicting constructors.

tests/compiler/dart2js/patch_test.dart

 // Copyright (c) 2012, 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/dart2jslib.dart";
 import "../../../sdk/lib/_internal/compiler/implementation/elements/elements.dart";
 import "../../../sdk/lib/_internal/compiler/implementation/tree/tree.dart";
 import "../../../sdk/lib/_internal/compiler/implementation/util/util.dart";
 import "mock_compiler.dart";
@@ skipping 123 matching lines @@
       """);
   var classOrigin = ensure(compiler, "Class", compiler.coreLibrary.find,
                            expectIsPatched: true);
   classOrigin.ensureResolved(compiler);
   var classPatch = ensure(compiler, "Class", compiler.coreLibrary.patch.find,
                           expectIsPatch: true);
 
   Expect.equals(classPatch, classOrigin.patch);
   Expect.equals(classOrigin, classPatch.origin);
 
-  var constructorOrigin = ensure(compiler, "Class",
+  var constructorOrigin = ensure(compiler, "",
                                  (name) => classOrigin.localLookup(name),
                                  expectIsPatched: true);
-  var constructorPatch = ensure(compiler, "Class",
+  var constructorPatch = ensure(compiler, "",
                                 (name) => classPatch.localLookup(name),
                                 expectIsPatch: true);
 
   Expect.equals(constructorPatch, constructorOrigin.patch);
   Expect.equals(constructorOrigin, constructorPatch.origin);
 
   Expect.isTrue(compiler.warnings.isEmpty,
                 "Unexpected warnings: ${compiler.warnings}");
   Expect.isTrue(compiler.errors.isEmpty,
                 "Unexpected errors: ${compiler.errors}");
@@ skipping 631 matching lines @@
   testPatchNoGetter();
   testPatchNonSetter();
   testPatchNoSetter();
   testPatchNonFunction();
 
   testPatchAndSelector();
 
   testAnalyzeAllInjectedMembers();
   testTypecheckPatchedMembers();
 }