[strong] Deprecate for-in

test/cctest/test-parsing.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 5530 matching lines @@
   static const ParserFlag always_flags[] = {
       kAllowStrongMode, kAllowHarmonyScoping
   };
   RunParserSyncTest(sloppy_context_data, data, kSuccess, NULL, 0, always_flags,
                     arraysize(always_flags));
   RunParserSyncTest(strict_context_data, data, kSuccess, NULL, 0, always_flags,
                     arraysize(always_flags));
   RunParserSyncTest(strong_context_data, data, kError, NULL, 0, always_flags,
                     arraysize(always_flags));
 }
+
+
+TEST(StrongForIn) {
+  const char* sloppy_context_data[][2] = {{"", ""}, {NULL}};
+  const char* strict_context_data[][2] = {{"'use strict';", ""}, {NULL}};
+  const char* strong_context_data[][2] = {{"'use strong';", ""}, {NULL}};
+
+  const char* data[] = {
+      "for (x in []) {}",
+      "for (const x in []) {}",
+      NULL};
+
+  static const ParserFlag always_flags[] = {
+      kAllowStrongMode, kAllowHarmonyScoping
+  };
+  RunParserSyncTest(sloppy_context_data, data, kSuccess, NULL, 0, always_flags,
+                    arraysize(always_flags));
+  RunParserSyncTest(strict_context_data, data, kSuccess, NULL, 0, always_flags,
+                    arraysize(always_flags));
+  RunParserSyncTest(strong_context_data, data, kError, NULL, 0, always_flags,
+                    arraysize(always_flags));
+}