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

core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.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/include/fpdfapi/fpdf_parser.h"
 
 #include <algorithm>
 #include <memory>
 #include <set>
 #include <utility>
 #include <vector>
 
+#include "core/include/fpdfapi/cpdf_document.h"
 #include "core/include/fpdfapi/fpdf_module.h"
 #include "core/include/fpdfapi/fpdf_page.h"
 #include "core/include/fxcrt/fx_ext.h"
 #include "core/include/fxcrt/fx_safe_types.h"
 #include "core/src/fpdfapi/fpdf_page/pageint.h"
 #include "core/src/fpdfapi/fpdf_parser/cpdf_syntax_parser.h"
 #include "core/src/fpdfapi/fpdf_parser/parser_int.h"
 #include "third_party/base/stl_util.h"
 
 namespace {
@@ skipping 4061 matching lines @@
   CPDF_Array* pRange = m_pLinearizedDict->GetArrayBy("H");
   if (!pRange)
     return -1;
 
   CPDF_Object* pStreamLen = pRange->GetElementValue(1);
   if (!pStreamLen)
     return -1;
 
   return pStreamLen->GetInteger();
 }