Added Base64 support in TextEncoder and TextDecoder.

Source/wtf/text/TextEncoding.h

 /*
  * Copyright (C) 2004, 2006, 2007, 2008, 2009 Apple 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 54 matching lines @@
     bool isUTF7Encoding() const;
 
     const char* m_name;
     UChar m_backslashAsCurrencySymbol;
 };
 
 inline bool operator==(const TextEncoding& a, const TextEncoding& b) { return a.name() == b.name(); }
 inline bool operator!=(const TextEncoding& a, const TextEncoding& b) { return a.name() != b.name(); }
 
 WTF_EXPORT const TextEncoding& ASCIIEncoding();
+WTF_EXPORT const TextEncoding& Base64Encoding();
 WTF_EXPORT const TextEncoding& Latin1Encoding();
 WTF_EXPORT const TextEncoding& UTF16BigEndianEncoding();
 WTF_EXPORT const TextEncoding& UTF16LittleEndianEncoding();
 WTF_EXPORT const TextEncoding& UTF32BigEndianEncoding();
 WTF_EXPORT const TextEncoding& UTF32LittleEndianEncoding();
 WTF_EXPORT const TextEncoding& UTF8Encoding();
 WTF_EXPORT const TextEncoding& WindowsLatin1Encoding();
 
 } // namespace WTF
 
 using WTF::ASCIIEncoding;
+using WTF::Base64Encoding;
 using WTF::Latin1Encoding;
 using WTF::UTF16BigEndianEncoding;
 using WTF::UTF16LittleEndianEncoding;
 using WTF::UTF32BigEndianEncoding;
 using WTF::UTF32LittleEndianEncoding;
 using WTF::UTF8Encoding;
 using WTF::WindowsLatin1Encoding;
 
 #endif // TextEncoding_h