Fix test that fails in checked mode: a factory must return a subtype of its defining class.

tests/lib/mirrors/mirrors_test.dart

 // Copyright (c) 2011, 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 MirrorsTest;
 import "dart:mirrors";
 import "../../../pkg/unittest/lib/unittest.dart";
 
 var topLevelField;
 u(a, b, c) => {"a": a, "b": b, "c": c};
 _v(a, b) => a + b;
 
 class Class<T> {

[regis, 2013/07/15 22:37:35]

Is there any particular reason why Class has a type parameter that is never
used?

[rmacnak, 2013/07/16 00:03:21]

Another test in this file inspects it reflectively.

   Class() { this.field = "default value"; }
   Class.withInitialValue(this.field);
   var field;
 
   Class.generative(this.field);
   Class.redirecting(y) : this.generative(y*2);
-  factory Class.faktory(y) => "FakeClass $y";
+  factory Class.faktory(y) => new Class.withInitialValue(y*3);
   factory Class.redirectingFactory(y) = Class.faktory;
 
   m(a, b, c) => {"a": a, "b": b, "c": c};
   _n(a, b) => a + b;
   noSuchMethod(invocation) => "DNU";
 
   static var staticField;
   static s(a, b, c) => {"a": a, "b": b, "c": c};
   static _t(a, b) => a + b;
 }
@@ skipping 152 matching lines @@
 
   instanceMirror = classMirror.newInstance(const Symbol('redirecting'),
                                            [8]);
   expect(instanceMirror.reflectee is Class, equals(true));
   expect(instanceMirror.reflectee.field, equals(16));
 
 
   if (!isDart2js) {
     instanceMirror = classMirror.newInstance(const Symbol('faktory'),
                                              [9]);
-    expect(instanceMirror.reflectee, equals('FakeClass 9'));
+    expect(instanceMirror.reflectee is Class, equals(true));
+    expect(instanceMirror.reflectee.field, equals(27));
+
 
     instanceMirror = classMirror.newInstance(const Symbol('redirectingFactory'),
                                              [10]);
-    expect(instanceMirror.reflectee, equals('FakeClass 10'));
+    expect(instanceMirror.reflectee is Class, equals(true));
+    expect(instanceMirror.reflectee.field, equals(30));
   }
 
 
   var future = classMirror.newInstanceAsync(const Symbol(''), []);
   future.then(expectAsync1((resultMirror) {
     var instance = resultMirror.reflectee;
     expect(instance is Class, equals(true));
     expect(instance.field, equals("default value"));
   }));
 
@@ skipping 76 matching lines @@
   });
   if (!isMinified) // TODO(ahe): Remove this line.
   test("Test simple and qualifiedName", () { testNames(mirrors, isDart2js); });
   if (isDart2js) return; // TODO(ahe): Remove this line.
   test("Test reflect type", () { testReflectClass(mirrors); });
 }
 
 main() {
   mainWithArgument();
 }