Split off CPDF_Document into its own .cpp/.h files.

core/src/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "core/src/fpdfapi/fpdf_page/pageint.h"
 
 #include <limits.h>
 
+#include "core/include/fpdfapi/cpdf_document.h"
 #include "core/include/fpdfapi/fpdf_module.h"
 #include "core/include/fpdfapi/fpdf_page.h"
 #include "core/include/fxcodec/fx_codec.h"
 #include "core/include/fxcrt/fx_ext.h"
 #include "core/include/fxcrt/fx_safe_types.h"
 
 CPDF_StreamParser::CPDF_StreamParser(const uint8_t* pData, FX_DWORD dwSize) {
   m_pBuf = pData;
   m_Size = dwSize;
   m_Pos = 0;
@@ skipping 848 matching lines @@
       }
       m_Status = Done;
       return;
     }
     steps++;
     if (pPause && pPause->NeedToPauseNow()) {
       break;
     }
   }
 }