Parse harmony let declarations.

src/scanner-base.cc

 // Copyright 2011 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 827 matching lines @@
   KEYWORD("for", FOR)                                         \
   KEYWORD("function", FUNCTION)                               \
   KEYWORD_GROUP('i')                                          \
   KEYWORD("if", IF)                                           \
   KEYWORD("implements", FUTURE_STRICT_RESERVED_WORD)          \
   KEYWORD("import", FUTURE_RESERVED_WORD)                     \
   KEYWORD("in", IN)                                           \
   KEYWORD("instanceof", INSTANCEOF)                           \
   KEYWORD("interface", FUTURE_STRICT_RESERVED_WORD)           \
   KEYWORD_GROUP('l')                                          \
-  KEYWORD("let", FUTURE_STRICT_RESERVED_WORD)                 \
+  KEYWORD("let", LET)                                         \
   KEYWORD_GROUP('n')                                          \
   KEYWORD("new", NEW)                                         \
   KEYWORD("null", NULL_LITERAL)                               \
   KEYWORD_GROUP('p')                                          \
   KEYWORD("package", FUTURE_STRICT_RESERVED_WORD)             \
   KEYWORD("private", FUTURE_STRICT_RESERVED_WORD)             \
   KEYWORD("protected", FUTURE_STRICT_RESERVED_WORD)           \
   KEYWORD("public", FUTURE_STRICT_RESERVED_WORD)              \
   KEYWORD_GROUP('r')                                          \
   KEYWORD("return", RETURN)                                   \
@@ skipping 175 matching lines @@
     }
     AddLiteralCharAdvance();
   }
   literal.Complete();
 
   next_.location.end_pos = source_pos() - 1;
   return true;
 }
 
 } }  // namespace v8::internal