Implement Object.hashCode()

dart/tests/language/hash_code_mangling_test.dart

Index: dart/tests/language/hash_code_mangling_test.dart
diff --git a/dart/tests/language/hash_code_mangling_test.dart b/dart/tests/language/hash_code_mangling_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..305951789b2b4ddc58b48db075c3514ee5caeb40
--- /dev/null
+++ b/dart/tests/language/hash_code_mangling_test.dart
@@ -0,0 +1,17 @@
+// 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.
+
+class Foo {
+  var $identityHash;
+}
+
+void main() {
+  Foo foo = new Foo();
+  foo.$identityHash = 'fisk';
+  Expect.isTrue(foo.$identityHash is String);
+  int hash = foo.hashCode();
+  Expect.isTrue(hash is int);
+  Expect.isTrue(foo.$identityHash is String);
+  Expect.equals(hash, foo.hashCode());
+}