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

core/src/fpdfapi/fpdf_render/fpdf_render_text.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_render/render_int.h"
 
+#include "core/include/fpdfapi/cpdf_document.h"
 #include "core/include/fpdfapi/fpdf_pageobj.h"
 #include "core/include/fpdfapi/fpdf_render.h"
 #include "core/include/fxge/fx_ge.h"
 #include "core/src/fpdfapi/fpdf_page/pageint.h"
 
 CPDF_Type3Cache::~CPDF_Type3Cache() {
   for (const auto& pair : m_SizeMap) {
     delete pair.second;
   }
   m_SizeMap.clear();
@@ skipping 758 matching lines @@
                   charpos.m_OriginY);
     path.m_Path.New()->Append(pPath, &matrix);
     path.m_Matrix = *pTextMatrix;
     path.m_bStroke = bStroke;
     path.m_FillType = bFill ? FXFILL_WINDING : 0;
     path.CalcBoundingBox();
     ProcessPath(&path, pObj2Device);
   }
 }