Fix OOB write in --print-code.

src/v8utils.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 246 matching lines @@
 
 void StringBuilder::AddFormatted(const char* format, ...) {
   va_list arguments;
   va_start(arguments, format);
   AddFormattedList(format, arguments);
   va_end(arguments);
 }
 
 
 void StringBuilder::AddFormattedList(const char* format, va_list list) {
-  ASSERT(!is_finalized() && position_ < buffer_.length());
+  ASSERT(!is_finalized() && position_ <= buffer_.length());
   int n = OS::VSNPrintF(buffer_ + position_, format, list);
   if (n < 0 || n >= (buffer_.length() - position_)) {
     position_ = buffer_.length();
   } else {
     position_ += n;
   }
 }
 
 } }  // namespace v8::internal