Remove "this==NULL" and adjust corresponding callers

core/src/fpdfapi/fpdf_page/fpdf_page_doc.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 "../../../include/fpdfapi/fpdf_page.h"
 #include "../../../include/fpdfapi/fpdf_module.h"
 #include "../../../include/fdrm/fx_crypt.h"
 #include "../fpdf_font/font_int.h"
@@ skipping 467 matching lines @@
         ptData = FX_NEW CPDF_CountedObject<CPDF_Pattern*>;
         bNew = TRUE;
         if (!ptData) {
             return NULL;
         }
     }
     CPDF_Pattern* pPattern = NULL;
     if (bShading) {
         pPattern = FX_NEW CPDF_ShadingPattern(m_pPDFDoc, pPatternObj, bShading, matrix);
     } else {
-        CPDF_Dictionary* pDict = pPatternObj->GetDict();
+        CPDF_Dictionary* pDict = pPatternObj ? pPatternObj->GetDict() : NULL;
         if (pDict) {
             int type = pDict->GetInteger(FX_BSTRC("PatternType"));
             if (type == 1) {
                 pPattern = FX_NEW CPDF_TilingPattern(m_pPDFDoc, pPatternObj, matrix);
             } else if (type == 2) {
                 pPattern = FX_NEW CPDF_ShadingPattern(m_pPDFDoc, pPatternObj, FALSE, matrix);
             }
         }
     }
     if (!pPattern) {
@@ skipping 139 matching lines @@
     m_FontFileMap.SetAt(pFontStream, ftData);
     return pFontFile;
 }
 void CPDF_DocPageData::ReleaseFontFileStreamAcc(CPDF_Stream* pFontStream, FX_BOOL bForce)
 {
     if (!pFontStream) {
         return;
     }
     PDF_DocPageData_Release<CPDF_Stream*, CPDF_StreamAcc*>(m_FontFileMap, pFontStream, NULL, bForce);
 }