Support the literal kind for native classes (ie Console).

frog/tests/native/src/NativeLiteralClassFrogTest.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.
+
+class A native "= {log: function() { return 42 } }" {
+  void log() native;
+}
+
+getA() native """
+  return A;
+""";
+
+bar() {
+  new A();
+}
+
+main() {
+  var a = getA();
+  // Make a call to bar to make sure A gets generated.
+  if (a is int) bar();
+  Expect.equals(42, a.log());
+}