Move frog/tests/{leg,leg_only,frog_native} to tests/compiler/.

frog/tests/leg_only/optional_parameter_test.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 {
-  foo([a]) {
-    return a;
-  }
-
-  bar(a, [b]) {
-    return b;
-  }
-
-  noSuchMethod(name, args) {
-    return 0;
-  }
-}
-
-main() {
-  A a = new A();
-  Expect.equals(42, a.foo(42));
-  Expect.equals(null, a.foo());
-  Expect.equals(null, a.bar(42));
-  Expect.equals(42, a.bar(null, 42));
-  Expect.equals(0, a.foo(1, 2));
-  Expect.equals(0, a.bar());
-  Expect.equals(0, a.bar(1, 2, 3));
-}