[es6] Initial support for let/const bindings in sloppy mode

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 6748 matching lines @@
   };
   // 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) {
+TEST(ConstLegacy) {
   // 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);
 }
+
+
+TEST(ConstSloppy) {
+  // clang-format off
+  const char* context_data[][2] = {
+    {"", ""},
+    {"{", "}"},
+    {NULL, NULL}
+  };
+
+  const char* data[] = {
+    "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[] = {kAllowHarmonySloppy,
+                                            kNoLegacyConst};
+  RunParserSyncTest(context_data, data, kSuccess, NULL, 0, always_flags,
+                    arraysize(always_flags));
+}
+
+
+TEST(LetSloppy) {
+  // clang-format off
+  const char* context_data[][2] = {
+    {"", ""},
+    {"'use strict';", ""},
+    {"{", "}"},
+    {NULL, NULL}
+  };
+
+  const char* data[] = {
+    "let x",
+    "let x = 1",
+    "for (let x = 1; x < 1; x++) {}",
+    "for (let x in {}) {}",
+    "for (let x of []) {}",
+    NULL
+  };
+  // clang-format on
+
+  static const ParserFlag always_flags[] = {kAllowHarmonySloppy};
+  RunParserSyncTest(context_data, data, kSuccess, NULL, 0, always_flags,
+                    arraysize(always_flags));
+}