Make native syntax an early error in the preparser.

src/preparser-api.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 170 matching lines @@
 PreParserData Preparse(UnicodeInputStream* input, size_t max_stack) {
   internal::InputStreamUTF16Buffer buffer(input);
   uintptr_t stack_limit = reinterpret_cast<uintptr_t>(&buffer) - max_stack;
   internal::UnicodeCache unicode_cache;
   internal::JavaScriptScanner scanner(&unicode_cache);
   scanner.Initialize(&buffer);
   internal::CompleteParserRecorder recorder;
   preparser::PreParser::PreParseResult result =
       preparser::PreParser::PreParseProgram(&scanner,
                                             &recorder,
-                                            true,
+                                            internal::kAllowLazy,
                                             stack_limit);
   if (result == preparser::PreParser::kPreParseStackOverflow) {
     return PreParserData::StackOverflow();
   }
   internal::Vector<unsigned> pre_data = recorder.ExtractData();
   size_t size = pre_data.length() * sizeof(pre_data[0]);
   unsigned char* data = reinterpret_cast<unsigned char*>(pre_data.start());
   return PreParserData(size, data);
 }
 
 }  // namespace v8.
 
 
 // Used by ASSERT macros and other immediate exits.
 extern "C" void V8_Fatal(const char* file, int line, const char* format, ...) {
   exit(EXIT_FAILURE);
 }