Tweaking WebPageSerializerImpl to emit a BOM for UTF16/32.

third_party/WebKit/Source/wtf/text/TextCodecUTF16.h

 /*
  * Copyright (C) 2004, 2006 Apple Computer, Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 22 matching lines @@
 class TextCodecUTF16 final : public TextCodec {
 public:
     static void registerEncodingNames(EncodingNameRegistrar);
     static void registerCodecs(TextCodecRegistrar);
 
     TextCodecUTF16(bool littleEndian) : m_littleEndian(littleEndian), m_haveBufferedByte(false) {}
 
     String decode(const char*, size_t length, FlushBehavior, bool stopOnError, bool& sawError) override;
     CString encode(const UChar*, size_t length, UnencodableHandling) override;
     CString encode(const LChar*, size_t length, UnencodableHandling) override;
+    bool shouldIncludeBOM() override;
 
 private:
     bool m_littleEndian;
     bool m_haveBufferedByte;
     unsigned char m_bufferedByte;
 };
 
 } // namespace WTF
 
 #endif // TextCodecUTF16_h