Prevent direct use of "replacement" text encoding.

Source/wtf/text/TextEncoding.cpp

 /*
  * Copyright (C) 2004, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov <ap@nypop.com>
  * Copyright (C) 2007-2009 Torch Mobile, Inc.
  *
  * 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.
@@ skipping 29 matching lines @@
 static const TextEncoding& UTF7Encoding()
 {
     static TextEncoding globalUTF7Encoding("UTF-7");
     return globalUTF7Encoding;
 }
 
 TextEncoding::TextEncoding(const char* name)
     : m_name(atomicCanonicalTextEncodingName(name))
     , m_backslashAsCurrencySymbol(backslashAsCurrencySymbol())
 {
+    // Aliases are valid, but not "replacement" itself.
+    if (m_name && isReplacementEncoding(name))
+        m_name = 0;
 }
 
 TextEncoding::TextEncoding(const String& name)
     : m_name(atomicCanonicalTextEncodingName(name))
     , m_backslashAsCurrencySymbol(backslashAsCurrencySymbol())
 {
+    // Aliases are valid, but not "replacement" itself.
+    if (m_name && isReplacementEncoding(name))
+        m_name = 0;
 }
 
 String TextEncoding::decode(const char* data, size_t length, bool stopOnError, bool& sawError) const
 {
     if (!m_name)
         return String();
 
     return newTextCodec(*this)->decode(data, length, DataEOF, stopOnError, sawError);
 }
 
@@ skipping 150 matching lines @@
     return globalUTF8Encoding;
 }
 
 const TextEncoding& WindowsLatin1Encoding()
 {
     static TextEncoding globalWindowsLatin1Encoding("WinLatin1");
     return globalWindowsLatin1Encoding;
 }
 
 } // namespace WTF