Re-apply "Implement operator== and hashCode for bound closures."

tests/language/bound_closure_primitives_test.dart

Index: tests/language/bound_closure_primitives_test.dart
===================================================================
--- tests/language/bound_closure_primitives_test.dart	(revision 0)
+++ tests/language/bound_closure_primitives_test.dart	(revision 0)
@@ -0,0 +1,27 @@
+// 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.
+
+// Test to make sure dart2js does not try to use the same
+// BoundClosureClass between an intercepted method and a
+// non-intercepted method.
+
+import "package:expect/expect.dart";
+
+class A {
+  // Make dart2js try to share a bound closure for [foo] with a bound
+  // closure for [List.add], by having same number of arguments.
+  foo(a) => a;
+}
+
+main() {
+  var array = [[], new A()];
+  var method = array[0].add;
+  method(42);
+
+  method = array[1].foo;
+  Expect.equals(42, method(42));
+
+  Expect.equals(1, array[0].length);
+  Expect.isTrue(array[0].contains(42));
+}