Add a flag for legacy const semantics

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 1418 matching lines @@
   kAllowHarmonyModules,
   kAllowHarmonyArrowFunctions,
   kAllowHarmonyRestParameters,
   kAllowHarmonySloppy,
   kAllowHarmonyUnicode,
   kAllowHarmonyComputedPropertyNames,
   kAllowHarmonySpreadCalls,
   kAllowHarmonyDestructuring,
   kAllowHarmonySpreadArrays,
   kAllowHarmonyNewTarget,
-  kAllowStrongMode
+  kAllowStrongMode,
+  kNoLegacyConst
 };
 
 
 enum ParserSyncTestResult {
   kSuccessOrError,
   kSuccess,
   kError
 };
 
 template <typename Traits>
@@ skipping 11 matching lines @@
   parser->set_allow_harmony_sloppy(flags.Contains(kAllowHarmonySloppy));
   parser->set_allow_harmony_unicode(flags.Contains(kAllowHarmonyUnicode));
   parser->set_allow_harmony_computed_property_names(
       flags.Contains(kAllowHarmonyComputedPropertyNames));
   parser->set_allow_harmony_destructuring(
       flags.Contains(kAllowHarmonyDestructuring));
   parser->set_allow_harmony_spread_arrays(
       flags.Contains(kAllowHarmonySpreadArrays));
   parser->set_allow_harmony_new_target(flags.Contains(kAllowHarmonyNewTarget));
   parser->set_allow_strong_mode(flags.Contains(kAllowStrongMode));
+  parser->set_allow_legacy_const(!flags.Contains(kNoLegacyConst));
 }
 
 
 void TestParserSyncWithFlags(i::Handle<i::String> source,
                              i::EnumSet<ParserFlag> flags,
                              ParserSyncTestResult result) {
   i::Isolate* isolate = CcTest::i_isolate();
   i::Factory* factory = isolate->factory();
 
   uintptr_t stack_limit = isolate->stack_guard()->real_climit();
@@ skipping 5274 matching lines @@
     kAllowHarmonyNewTarget,
     kAllowHarmonySloppy,
   };
   // clang-format on
 
   RunParserSyncTest(good_context_data, data, kSuccess, NULL, 0, always_flags,
                     arraysize(always_flags));
   RunParserSyncTest(bad_context_data, data, kError, NULL, 0, always_flags,
                     arraysize(always_flags));
 }
+
+
+TEST(LegacyConst) {
+  // clang-format off
+  const char* context_data[][2] = {
+    {"", ""},
+    {"{", "}"},
+    {NULL, NULL}
+  };
+
+  const char* data[] = {
+    "const x",
+    "const x = 1",
+    "for (const x = 1; x < 1; x++) {}",
+    "for (const x in {}) {}",
+    "for (const x of []) {}",
+    NULL
+  };
+  // clang-format on
+
+  static const ParserFlag always_flags[] = {kNoLegacyConst};
+
+  RunParserSyncTest(context_data, data, kError, NULL, 0, always_flags,
+                    arraysize(always_flags));
+  RunParserSyncTest(context_data, data, kSuccess);
+}