src: remove misleading flag in TwoByteValue

String::REPLACE_INVALID_UTF8 is only applied in V8's
String::WriteUtf8() (i.e. Utf8Value).

PR-URL: https://github.com/nodejs/node/pull/11436
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>

src/util.cc

@@ -48,8 +48,7 @@ TwoByteValue::TwoByteValue(Isolate* isolate, Local<Value> value) {
   const size_t storage = string->Length() + 1;
   AllocateSufficientStorage(storage);
 
-  const int flags =
+  const int flags = String::NO_NULL_TERMINATION;
-      String::NO_NULL_TERMINATION | String::REPLACE_INVALID_UTF8;
   const int length = string->Write(out(), 0, storage, flags);
   SetLengthAndZeroTerminate(length);
 }