Fix VPrintHelper used on Windows.

src/platform-win32.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 644 matching lines @@
         GetFileType(GetStdHandle(STD_OUTPUT_HANDLE)) != FILE_TYPE_UNKNOWN)
       output_mode = CONSOLE;
     else
       output_mode = ODS;
   }
   return output_mode == CONSOLE;
 }
 
 
 static void VPrintHelper(FILE* stream, const char* format, va_list args) {
-  if (HasConsole()) {
-    vfprintf(stream, format, args);
-  } else {
+  if ((stream == stdout || stream == stderr) && !HasConsole()) {
     // It is important to use safe print here in order to avoid
     // overflowing the buffer. We might truncate the output, but this
     // does not crash.
     EmbeddedVector<char, 4096> buffer;
     OS::VSNPrintF(buffer, format, args);
     OutputDebugStringA(buffer.start());
+  } else {
+    vfprintf(stream, format, args);
   }
 }
 
 
 FILE* OS::FOpen(const char* path, const char* mode) {
   FILE* result;
   if (fopen_s(&result, path, mode) == 0) {
     return result;
   } else {
     return NULL;
@@ skipping 821 matching lines @@
   ASSERT(result);
 }
 
 
 
 void Thread::YieldCPU() {
   Sleep(0);
 }
 
 } }  // namespace v8::internal