Make Document.inputEncoding an explicit alias of Document.characterSet

Source/core/loader/TextResourceDecoderBuilder.cpp

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * 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
@@ skipping 71 matching lines @@
     // that can be mistaken for hintEncoding (or related encoding) by
     // an auto detector. When interpreted in the latter, it could be
     // an attack vector.
     // FIXME: This might be too cautious for non-7bit-encodings and
     // we may consider relaxing this later after testing.
     if (frame && canReferToParentFrameEncoding(frame, parentFrame)) {
         if (parentFrame->document()->encodingWasDetectedHeuristically())
             decoder->setHintEncoding(parentFrame->document()->encoding());
 
         if (m_encoding.isEmpty())
-            decoder->setEncoding(parentFrame->document()->inputEncoding().string(), TextResourceDecoder::EncodingFromParentFrame);
+            decoder->setEncoding(parentFrame->document()->encoding(), TextResourceDecoder::EncodingFromParentFrame);
     }
 }
 
 PassOwnPtr<TextResourceDecoder> TextResourceDecoderBuilder::buildFor(Document* document)
 {
     OwnPtr<TextResourceDecoder> decoder = createDecoderInstance(document);
     setupEncoding(decoder.get(), document);
     return decoder.release();
 }
 
 void TextResourceDecoderBuilder::clear()
 {
     m_encoding = nullAtom;
 }
 
 }