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

frog/tests/leg/boolify_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.
-
-#library("boolified_operator_test.dart");
-#import("compiler_helper.dart");
-
-final String TEST = @"""
-foo() {
-  var a = foo();
-  if (!a) return 1;
-  return 2;
-}
-""";
-
-main() {
-  String generated = compile(TEST, 'foo');
-  Expect.isTrue(generated.contains('foo() !== true)'));
-}