Canonicalize closures passed to native functions.

frog/tests/native/src/NativeClosureIdentityFrogTest.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.
+
+typedef void MyFunctionType();
+
+class A native "*A" {
+  setClosure(MyFunctionType f) native;
+  check(MyFunctionType f) native;
+  invoke() native;
+}
+
+makeA() native { return new A(); }
+
+void setup() native """
+function A() {}
+A.prototype.setClosure = function(f) { this.f = f; };
+A.prototype.check = function(f) { return this.f === f; };
+A.prototype.invoke = function() { return this.f(); };
+makeA = function(){return new A;};
+""";
+
+var staticClosure;
+staticMethod() => 42;
+
+class B {
+  var instanceClosure;
+  instanceMethod() => 43;
+}
+
+checkUntyped(a, closure) {
+  a.setClosure(closure);
+  Expect.isTrue(a.check(closure));
+  Expect.equals(closure(), a.invoke());
+}
+
+checkTyped(A a, MyFunctionType closure) {
+  a.setClosure(closure);
+  Expect.isTrue(a.check(closure));
+  Expect.equals(closure(), a.invoke());
+}
+
+main() {
+  setup();
+
+  staticClosure = () => 44;
+  B b = new B();
+  b.instanceClosure = () => 45;
+
+  closureStatement() => 46;
+  var closureExpression = () => 47;
+
+  checkUntyped(makeA(), staticClosure);
+  checkTyped(makeA(), staticClosure);
+
+  checkUntyped(makeA(), staticMethod);
+  checkTyped(makeA(), staticMethod);
+
+  checkUntyped(makeA(), b.instanceClosure);
+  checkTyped(makeA(), b.instanceClosure);
+
+  checkUntyped(makeA(), b.instanceMethod);
+  checkTyped(makeA(), b.instanceMethod);
+
+  checkUntyped(makeA(), closureStatement);
+  checkTyped(makeA(), closureStatement);
+
+  checkUntyped(makeA(), closureExpression);
+  checkTyped(makeA(), closureExpression);
+}