Avoid mangling the name of native methods.

frog/tests/native/src/NativeMethodWithKeywordNameTest.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.
+
+// Make sure we can have a native with a name that is a JavaScript keyword.
+
+class A native "*A" {
+  int delete() native;
+}
+
+A makeA() native { return new A(); }
+
+void setup() native """
+function A() {}
+A.prototype.delete = function() { return 87; };
+
+makeA = function(){return new A;};
+""";
+
+
+main() {
+  setup();
+
+  var a = makeA();
+  Expect.equals(87, a.delete());
+  A aa = a;
+  Expect.equals(87, aa.delete());  
+}