We must use the original element and not the default implementation element when checking if the co…

frog/tests/leg/src/mock_compiler.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.
 
 #library('mock_compiler');
 
 #import("dart:uri");
 
 #import("../../../../lib/compiler/implementation/elements/elements.dart");
 #import("../../../../lib/compiler/implementation/leg.dart");
@@ skipping 30 matching lines @@
 
 final String DEFAULT_CORELIB = @'''
   print(var obj) {}
   class int {}
   class double {}
   class bool {}
   class String {}
   class Object {}
   class num {}
   class Function {}
-  class List {}
+  class List { factory List() => null; }
   class Closure {}
   class Null {}
   class Dynamic {}''';
 
 class MockCompiler extends Compiler {
   List<WarningMessage> warnings;
   List<WarningMessage> errors;
   final Map<String, String> sources;
   Node parsedTree;
 
@@ skipping 126 matching lines @@
   importLibrary(library, compiler.coreLibrary, compiler);
   return library;
 }
 
 class StringScript extends Script {
   final String code;
   StringScript(this.code) : super(null, null);
   String get text() => code;
   String get name() => "mock script";
 }