String:WriteUtf8: Add REPLACE_INVALID_UTF8 option

src/objects.cc

 // Copyright 2013 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 8294 matching lines @@
   // Convert the UTF-16 string to a UTF-8 buffer. Start at the specified offset.
   stream.Reset(this, offset);
   character_position = offset;
   int utf8_byte_position = 0;
   last = unibrow::Utf16::kNoPreviousCharacter;
   while (stream.HasMore() && character_position++ < offset + length) {
     uint16_t character = stream.GetNext();
     if (allow_nulls == DISALLOW_NULLS && character == 0) {
       character = ' ';
     }
+    // @TODO Fix this Utf8::Encode call site somehow.
     utf8_byte_position +=
         unibrow::Utf8::Encode(result + utf8_byte_position, character, last);
     last = character;
   }
   result[utf8_byte_position] = 0;
   return SmartArrayPointer<char>(result);
 }
 
 
 SmartArrayPointer<char> String::ToCString(AllowNullsFlag allow_nulls,
@@ skipping 8341 matching lines @@
 #define ERROR_MESSAGES_TEXTS(C, T) T,
   static const char* error_messages_[] = {
       ERROR_MESSAGES_LIST(ERROR_MESSAGES_TEXTS)
   };
 #undef ERROR_MESSAGES_TEXTS
   return error_messages_[reason];
 }
 
 
 } }  // namespace v8::internal